Fix format-truncation and strncpy compiler warnings

[mikelolasagasti]

Increased buffer sizes in utils.c and ui.c to accommodate the full range of integer values (preventing possible truncation).

Replaced strncpy with snprintf in ui.c to ensure destination buffers are always null-terminated and free of garbage data.

Fixes the following warning:

/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c: In function ‘amount_to_str’: /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c:371:52: warning: ‘__snprintf_chk’ output may be truncated before the last format character [-Wformat-truncation=]
  371 |                 snprintf(out, AMOUNT_STR_LEN, "%dKB", (int)((amount + M_KB - 1) / M_KB));
      |                                                    ^
In file included from /usr/include/stdio.h:974,
                 from /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c:7:
In function ‘snprintf’,
    inlined from ‘amount_to_str’ at /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c:371:3:
/usr/include/bits/stdio2.h:68:10: note: ‘__snprintf_chk’ output between 4 and 7 bytes into a destination of size 6
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c: In function ‘amount_to_str’:
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c:369:52: warning: ‘__snprintf_chk’ output may be truncated before the last format character [-Wformat-truncation=]
  369 |                 snprintf(out, AMOUNT_STR_LEN, "%dMB", (int)((amount + M_MB - 1) / M_MB));
      |                                                    ^
In function ‘snprintf’,
    inlined from ‘amount_to_str’ at /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/utils.c:369:3:
/usr/include/bits/stdio2.h:68:10: note: ‘__snprintf_chk’ output between 4 and 7 bytes into a destination of size 6
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c: In function ‘edit_color’:
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:155:69: warning: ‘%d’ directive output may be truncated writing between 1 and 6 bytes into a region of size 5 [-Wformat-truncation=]
  155 |                                 snprintf(val_str, sizeof(val_str), "%d", val);
      |                                                                     ^~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:155:68: note: directive argument in the range [-32768, 32767]
  155 |                                 snprintf(val_str, sizeof(val_str), "%d", val);
      |                                                                    ^~~~
In file included from /usr/include/stdio.h:974,
                 from /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:5:
In function ‘snprintf’,
    inlined from ‘edit_color’ at /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:155:5:
/usr/include/bits/stdio2.h:68:10: note: ‘__snprintf_chk’ output between 2 and 7 bytes into a destination of size 5
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c: In function ‘set_window_sizes’:
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:2168:83: warning: ‘%d’ directive output may be truncated writing between 1 and 10 bytes into a region of size 5 [-Wformat-truncation=]
 2168 |                                                 snprintf(oldval, sizeof(oldval), "%d", pi[window].win_height);
      |                                                                                   ^~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:2168:82: note: directive argument in the range [0, 2147483647]
 2168 |                                                 snprintf(oldval, sizeof(oldval), "%d", pi[window].win_height);
      |                                                                                  ^~~~
In function ‘snprintf’,
    inlined from ‘set_window_sizes’ at /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:2168:7:
/usr/include/bits/stdio2.h:68:10: note: ‘__snprintf_chk’ output between 2 and 11 bytes into a destination of size 5
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c: In function ‘edit_regexp’:
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:1165:33: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-truncation]
 1165 |                                 strncpy(dummy, (cur -> pre)[loop].cmd, min(17, strlen((cur -> pre)[loop].cmd)));
      |                                 ^
In file included from /builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:24:
/builddir/build/BUILD/multitail-7.1.5-build/multitail-7.1.5/ui.c:1165:80: note: length computed here
 1165 |                                 strncpy(dummy, (cur -> pre)[loop].cmd, min(17, strlen((cur -> pre)[loop].cmd)));

[folkertvanheusden]

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