for the machine ("i386" or "ppc"), even if the executable is
64-bit.

This patchs ensures that the distutils platform architecture
represents the architecture for the executable when running a
64-bit only executable on OSX.

on OSX. Without this patch it wasn't possible after all
to compile extensions on OSX 10.6 with the binary
installer unless the user had installed the (non-default)
10.4u SDK.

Issue #7457: added a read_pkg_file method to distutils.dist.DistributionMetadata so we can read back PKG-INFO files

extensions with msvc9compiler.

ignores the '-isysroot' option on OSX when the
corresponding SDK is not installed.

This ensures that the user can compile extensions
on OSX 10.6 using the Python.org installer and a
default installation of Xcode.