Fix espeak build

[danemadsen]

This is a simple patch to fix an error im getting when trying to build on linux

[ 22%] Linking C shared library libespeak-ng.so
/usr/bin/ld: ../ucd-tools/libucd.a(case.c.o): relocation R_X86_64_32S against `.rodata' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: failed to set dynamic section sizes: bad value
collect2: error: ld returned 1 exit status
gmake[6]: *** [src/libespeak-ng/CMakeFiles/espeak-ng.dir/build.make:514: src/libespeak-ng/libespeak-ng.so.1.52.0.1] Error 1
gmake[5]: *** [CMakeFiles/Makefile2:1094: src/libespeak-ng/CMakeFiles/espeak-ng.dir/all] Error 2
gmake[4]: *** [Makefile:166: all] Error 2
gmake[3]: *** [CMakeFiles/espeak_ng_external.dir/build.make:86: e/src/espeak_ng_external-stamp/espeak_ng_external-build] Error 2
gmake[2]: *** [CMakeFiles/Makefile2:143: CMakeFiles/espeak_ng_external.dir/all] Error 2
gmake[1]: *** [Makefile:146: all] Error 2
gmake[1]: Leaving directory '/home/danemadsen/piper_tts/src/piper-phonemize/build'
make: *** [Makefile:5: all] Error 2