PkgConfig use 'separate_arguments' for pkgconfig result, so output
converted to the list (in cmake it's semicolumnt separated values).
If we try to append CFLAGS_OTHER as is, it will provide error for
more then one cflag in '.pc' file
Fix#4175, fix#4457.
One part fixes#4280 (removing this flag giving qTox on Windows able to start properly), another part fixes my mistake in #4258 (strmiids still needed for
linking, but previous searching of this libstrmiids.a wasn't include, for example, '/mingw32/i686-w64-mingw32/lib'. So I just add this lib to $ALL_LIBRARIES,
because it exists in system by default).
Fixes bulding with cmake on Windows. strmiids is exists as a
libstrmiids.a static library, but cmake can't find it. Because of
useless of this search and successful building without it, I'm removed it.
