dev-lang/python: fix system libffi handling

dev-lang/python/files/python-2.7.10-system-libffi.patch

@@ -0,0 +1,36 @@
+make sure we respect the system libffi setting in our build config.
+the compiler probing is fragile and can break in some situations.
+
+--- a/setup.py
++++ b/setup.py
+@@ -2069,7 +2069,7 @@ class PyBuildExt(build_ext):
+ return True
+
+ def detect_ctypes(self, inc_dirs, lib_dirs):
+- self.use_system_libffi = False
++ self.use_system_libffi = ('--with-system-ffi' in sysconfig.get_config_var("CONFIG_ARGS"))
+ include_dirs = []
+ extra_compile_args = []
+ extra_link_args = []
+@@ -2113,7 +2113,7 @@ class PyBuildExt(build_ext):
+ sources=['_ctypes/_ctypes_test.c'])
+ self.extensions.extend([ext, ext_test])
+
+- if not '--with-system-ffi' in sysconfig.get_config_var("CONFIG_ARGS"):
++ if not self.use_system_libffi:
+ return
+
+ if host_platform == 'darwin':
+@@ -2141,10 +2141,10 @@ class PyBuildExt(build_ext):
+ ffi_lib = lib_name
+ break
+
+- if ffi_inc and ffi_lib:
++ if ffi_inc:
+ ext.include_dirs.extend(ffi_inc)
++ if ffi_lib:
+ ext.libraries.append(ffi_lib)
+- self.use_system_libffi = True
+
+
+ class PyBuildInstall(install):

dev-lang/python/python-2.7.10-r3.ebuild

@@ -101,6 +101,7 @@ src_prepare() {
  epatch "${FILESDIR}/python-2.7.5-nonfatal-compileall.patch"
  epatch "${FILESDIR}/python-2.7.9-ncurses-pkg-config.patch"
  epatch "${FILESDIR}/python-2.7.10-cross-compile-warn-test.patch"
+ epatch "${FILESDIR}/python-2.7.10-system-libffi.patch"
 
  sed -i -e "s:@@GENTOO_LIBDIR@@:$(get_libdir):g" \
  Lib/distutils/command/install.py \

dev-lang/python/python-2.7.10-r4.ebuild

@@ -102,6 +102,7 @@ src_prepare() {
  epatch "${FILESDIR}/python-2.7.5-nonfatal-compileall.patch"
  epatch "${FILESDIR}/python-2.7.9-ncurses-pkg-config.patch"
  epatch "${FILESDIR}/python-2.7.10-cross-compile-warn-test.patch"
+ epatch "${FILESDIR}/python-2.7.10-system-libffi.patch"
 
  sed -i -e "s:@@GENTOO_LIBDIR@@:$(get_libdir):g" \
  Lib/distutils/command/install.py \