Fix preprocessor definitions for wxBase build under OS X.

Define __WXOSX__ for non-GUI build under Darwin. Ensure that the rest of the
code compiles correctly when just __WXOSX__ is defined but neither of
__WXOSX_{CARBON,COCOA,IPHONE}__ is. This ensures that wxBase can actually be
built under Mac.

Move OS X symbols definitions in wx/platform.h after wx/setup.h inclusion as
they rely on __DARWIN__ and wxUSE_GUI values which are both define in that
file now. Still keep them before wx/chkconf.h inclusion which relies on
__WXOSX_XXX__ being defined. Yes, it's a mess and should be cleaned up more
permanently some day.

Also remove some redundancy from wx/osx/{carbon,cocoa}/private.h by factoring
out common parts into wx/osx/core/private.h. Also include this header itself
from wx/osx/private.h directly instead of including it thrice from different
sub-ports headers.

Closes #12660.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66077 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/osx/carbon/private.h

@@ -14,10 +14,6 @@
 #ifndef _WX_PRIVATE_H_
 #define _WX_PRIVATE_H_
 
-#include "wx/osx/core/private.h"
-
-#include <Carbon/Carbon.h>
-
 #if MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_5
 typedef UInt32 URefCon;
 typedef SInt32 SRefCon;
@@ -942,16 +938,6 @@ UPP Get##x()                                \
     return sHandler;                        \
 }
 
-//---------------------------------------------------------------------------
-// wxMac string conversions
-//---------------------------------------------------------------------------
-
-// filefn.cpp
-
-WXDLLIMPEXP_BASE wxString wxMacFSRefToPath( const FSRef *fsRef , CFStringRef additionalPathComponent = NULL );
-WXDLLIMPEXP_BASE OSStatus wxMacPathToFSRef( const wxString&path , FSRef *fsRef );
-WXDLLIMPEXP_BASE wxString wxMacHFSUniStrToString( ConstHFSUniStr255Param uniname );
-
 //---------------------------------------------------------------------------
 // cocoa bridging utilities
 //---------------------------------------------------------------------------