[libepoxy,libcares,physfs] Do not call `vcpkg_fixup_pkgconfig`

See epoxy.pc for example:

```pc
prefix=/Users/nimazzuc/projects/vcpkg/packages/libepoxy_arm64-osx # <- this is incorrect
libdir=${prefix}/lib
includedir=${prefix}/include

epoxy_has_glx=0
epoxy_has_egl=0
epoxy_has_wgl=0

Name: epoxy
Description: GL dispatch library
Version: 1.5.5
Libs: -L${libdir} -lepoxy -ldl
Cflags: -I${includedir}
```