[build] Move mac support code to `mac-support.h'.

* builds/unix/ftconfig.h.in, builds/vms/ftconfig.h,
include/freetype/config/ftconfig.h: Split off mac-specific stuff
to...
* include/freetype/config/mac-support.h: ...this new file.

* CMakeLists.txt, builds/unix/configure.raw: Remove `/undef ->
#undef' string replacement; the affected code is no longer part of
the `ftconfig.h' template.
7 files changed