It would never have been used in a configure build since setup.h which defines
__UNIX__ is included from platform.h before the if/elif block. Likewise, it
would not have been used for wxMac Xcode builds since they use config_xcode.h
which also defines __UNIX__. That's fortunate since __POWERPC__ was defined
unconditionally in that case. Note that classic builds wouldn't have used
the case either since they have their own case just before it (which remains).
Add __MACH__ to the list of UNIX defines (e.g. like __hpux) so that the UNIX
case of the OS if/elif block is guaranteed to match for all Mach systems. In
addition to that, within that case check for __APPLE__ && __MACH__ and make
sure that __BSD__ and __DARWIN__ are defined, TARGET_CARBON is defined,
and wxSIZE_T_IS_ULONG is defined.
Add __ppc__ to the list of defines that will cause __POWERPC__ to be defined
although it's interesting to note that we don't seem to use it anywhere.
Make sure that each case of the OS if/elif block has a /* OS ... */ comment
to make the code a bit easier to follow.
Remove comment about __DARWIN__ being used to work around defects in GCC,
that was removed years ago.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49408 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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