MacOS X: Enable 4-way universal builds

This patch adds a new configure argument on OSX:
        --with-universal-archs=[32-bit|64-bit|all]

When used with the --enable-universalsdk option this controls which
CPU architectures are includes in the framework. The default is 32-bit,
meaning i386 and ppc. The most useful alternative is 'all', which includes
all 4 CPU architectures supported by MacOS X (i386, ppc, x86_64 and ppc64).

This includes limited support for the Carbon bindings in 64-bit mode as well,
limited because (a) I haven't done extensive testing and (b) a large portion
of the Carbon API's aren't available in 64-bit mode anyway.

I've also duplicated a feature of Apple's build of python: setting the
environment variable 'ARCHFLAGS' controls the '-arch' flags used for building
extensions using distutils.

sysconfig.py

@@ -539,6 +539,26 @@ def get_config_vars(*args):
                     flags = re.sub('-isysroot [^ \t]*', ' ', flags)
                     _config_vars[key] = flags
 
+            else:
+
+                # Allow the user to override the architecture flags using
+                # an environment variable.
+                # NOTE: This name was introduced by Apple in OSX 10.5 and
+                # is used by several scripting languages distributed with
+                # that OS release.
+
+                if 'ARCHFLAGS' in os.environ:
+                    arch = os.environ['ARCHFLAGS']
+                    for key in ('LDFLAGS', 'BASECFLAGS',
+                        # a number of derived variables. These need to be
+                        # patched up as well.
+                        'CFLAGS', 'PY_CFLAGS', 'BLDSHARED'):
+
+                        flags = _config_vars[key]
+                        flags = re.sub('-arch\s+\w+\s', ' ', flags)
+                        flags = flags + ' ' + arch
+                        _config_vars[key] = flags
+
     if args:
         vals = []
         for name in args:

unixccompiler.py

@@ -64,7 +64,7 @@ def _darwin_compiler_fixup(compiler_so, cc_args):
         stripArch = '-arch' in cc_args
         stripSysroot = '-isysroot' in cc_args
 
-    if stripArch:
+    if stripArch or 'ARCHFLAGS' in os.environ:
         while 1:
             try:
                 index = compiler_so.index('-arch')
@@ -73,6 +73,12 @@ def _darwin_compiler_fixup(compiler_so, cc_args):
             except ValueError:
                 break
 
+    if 'ARCHFLAGS' in os.environ and not stripArch:
+        # User specified different -arch flags in the environ,
+        # see also distutils.sysconfig
+        compiler_so = compiler_so + ' ' + os.environ['ARCHFLAGS']
+
+
     if stripSysroot:
         try:
             index = compiler_so.index('-isysroot')

util.py

@@ -125,12 +125,19 @@ def get_platform ():
             osname = "macosx"
 
 
-            if (release + '.') < '10.4.' and \
-                    get_config_vars().get('UNIVERSALSDK', '').strip():
+            if (release + '.') >= '10.4.' and \
+                    '-arch' in get_config_vars().get('CFLAGS', '').strip():
                 # The universal build will build fat binaries, but not on
                 # systems before 10.4
+                #
+                # Try to detect 4-way universal builds, those have machine-type
+                # 'universal' instead of 'fat'.
+
                 machine = 'fat'
 
+                if '-arch x86_64' in get_config_vars().get('CFLAGS'):
+                    machine = 'universal'
+
             elif machine in ('PowerPC', 'Power_Macintosh'):
                 # Pick a sane name for the PPC architecture.
                 machine = 'ppc'