Support BSD-like sed syntax on macOS

[TheZ3ro]

On macOS, the system-wide sed use the -i flag for a different purpose:

SED(1)                                                         General Commands Manual

NAME
     sed – stream editor

SYNOPSIS
     sed [-EHalnru] command [-I extension] [-i extension] [file ...]
     sed [-EHalnru] [-e command] [-f command_file] [-I extension] [-i extension] [file ...]

this breaks the installation since the current folder (in $PACKAGE_LIST, that is something like /usr/local/vitasdk) will be interpreted as a sed command