fix(dev-lang/python): Update python build for cross-compiling.

Port the ChromiumOS distutils and site patches from 2.7.3 to 2.7.5 and
add some additional exports to make autoconf happy.

sdk_container/src/third_party/coreos-overlay/dev-lang/python/files/python-2.7.5-cross-distutils.patch

@@ -0,0 +1,96 @@
+diff --git a/Lib/distutils/command/build_ext.py b/Lib/distutils/command/build_ext.py
+index 923197b..b6ee689 100644
+--- a/Lib/distutils/command/build_ext.py
++++ b/Lib/distutils/command/build_ext.py
+@@ -239,7 +239,8 @@ class build_ext (Command):
+             and sysconfig.get_config_var('Py_ENABLE_SHARED')):
+             if sys.executable.startswith(os.path.join(sys.exec_prefix, "bin")):
+                 # building third party extensions
+-                self.library_dirs.append(sysconfig.get_config_var('LIBDIR'))
++                sysroot = os.getenv('SYSROOT', '')
++                self.library_dirs.append(sysroot + sysconfig.get_config_var('LIBDIR'))
+             else:
+                 # building python standard extensions
+                 self.library_dirs.append('.')
+diff --git a/Lib/distutils/command/install.py b/Lib/distutils/command/install.py
+index a2822e8..ab7f8e8 100644
+--- a/Lib/distutils/command/install.py
++++ b/Lib/distutils/command/install.py
+@@ -41,8 +41,8 @@ else:
+ 
+ INSTALL_SCHEMES = {
+     'unix_prefix': {
+-        'purelib': '$base/@@GENTOO_LIBDIR@@/python$py_version_short/site-packages',
+-        'platlib': '$platbase/@@GENTOO_LIBDIR@@/python$py_version_short/site-packages',
++        'purelib': '$base/$libdirname/python$py_version_short/site-packages',
++        'platlib': '$platbase/$libdirname/python$py_version_short/site-packages',
+         'headers': '$base/include/python$py_version_short/$dist_name',
+         'scripts': '$base/bin',
+         'data'   : '$base',
+@@ -319,6 +319,7 @@ class install (Command):
+         # everything else.
+         self.config_vars['base'] = self.install_base
+         self.config_vars['platbase'] = self.install_platbase
++        self.config_vars['libdirname'] = self.install_libdirname
+ 
+         if DEBUG:
+             from pprint import pprint
+@@ -435,6 +436,10 @@ class install (Command):
+ 
+             self.install_base = self.prefix
+             self.install_platbase = self.exec_prefix
++            self.install_libdirname = os.path.basename(get_config_vars('LIBDIR')[0])
++            if self.install_libdirname is None:
++                self.install_libdirname = '@@GENTOO_LIBDIR@@'
++
+             self.select_scheme("unix_prefix")
+ 
+     # finalize_unix ()
+diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
+index e16b05c..c67434a 100644
+--- a/Lib/distutils/sysconfig.py
++++ b/Lib/distutils/sysconfig.py
+@@ -19,9 +19,16 @@ import sys
+ from distutils.errors import DistutilsPlatformError
+ 
+ # These are needed in a couple of spots, so just compute them once.
++SYSROOT = os.getenv('SYSROOT', '')
+ PREFIX = os.path.normpath(sys.prefix)
+ EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
+ 
++# Make sure we respect the user specified SYSROOT environment variable.
++# This is the first step to get distutils to crosscompile stuff.
++if SYSROOT:
++    PREFIX = os.path.normpath(SYSROOT + os.path.sep + PREFIX)
++    EXEC_PREFIX = os.path.normpath(SYSROOT + os.path.sep + EXEC_PREFIX)
++
+ # Path to the base directory of the project. On Windows the binary may
+ # live in project/PCBuild9.  If we're dealing with an x64 Windows build,
+ # it'll live in project/PCbuild/amd64.
+@@ -114,13 +121,21 @@ def get_python_lib(plat_specific=0, standard_lib=0, prefix=None):
+ 
+     If 'prefix' is supplied, use it instead of sys.prefix or
+     sys.exec_prefix -- i.e., ignore 'plat_specific'.
++
++    For the posix system we can not always assume the host's notion of the
++    libdir is the same for the target.  e.g. compiling on an x86_64 system
++    will use 'lib64' but an arm 32bit target will use 'lib'.  So encode all
++    the known lists of dirs and search them all (starting with the host one
++    so that native builds work just fine).
+     """
+     if prefix is None:
+         prefix = plat_specific and EXEC_PREFIX or PREFIX
+ 
+     if os.name == "posix":
+-        libpython = os.path.join(prefix,
+-                                 "@@GENTOO_LIBDIR@@", "python" + get_python_version())
++        for libdir in ['@@GENTOO_LIBDIR@@', 'lib64', 'lib32', 'libx32', 'lib']:
++            libpython = os.path.join(prefix, libdir, "python" + get_python_version())
++            if os.path.exists(libpython):
++                break
+         if standard_lib:
+             return libpython
+         else:
+-- 
+1.8.1.5
+

sdk_container/src/third_party/coreos-overlay/dev-lang/python/python-2.7.5-r2.ebuild

@@ -102,6 +102,17 @@ src_prepare() {
 	epatch "${FILESDIR}/${P}-re_unsigned_ptrdiff.patch" #476426
 	epatch "${FILESDIR}/CVE-2013-4238_py27.patch"
 
+	#
+	# START: ChromiumOS specific changes
+	#
+	epatch "${FILESDIR}"/python-2.7.5-cross-distutils.patch
+
+	sed -i -e "s:sys.exec_prefix]:sys.exec_prefix, '/usr/local']:g" \
+		Lib/site.py || die "sed failed to add /usr/local to prefixes"
+	#
+	# END: ChromiumOS specific changes
+	#
+
 	sed -i -e "s:@@GENTOO_LIBDIR@@:$(get_libdir):g" \
 		Lib/distutils/command/install.py \
 		Lib/distutils/sysconfig.py \
@@ -183,6 +194,10 @@ src_configure() {
 		# The configure script assumes it's buggy when cross-compiling.
 		export ac_cv_buggy_getaddrinfo=no
 		export ac_cv_have_long_long_format=yes
+
+		# The configure script requires this to be explicit
+		export ac_cv_file__dev_ptmx=yes
+		export ac_cv_file__dev_ptc=no
 	fi
 
 	# Export CXX so it ends up in /usr/lib/python2.X/config/Makefile.