cffi: add upstream PKG_CONFIG fix

BUG=chromium:985180
TEST=CQ passes

Change-Id: Ia53b13752766e3ed157f68eb556b4441e8d3d6cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2213180
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/dev-python/cffi/cffi-1.11.4.ebuild b/dev-python/cffi/cffi-1.11.4.ebuild
index 97d00c4..ed05407 100644
--- a/dev-python/cffi/cffi-1.11.4.ebuild
+++ b/dev-python/cffi/cffi-1.11.4.ebuild
@@ -7,7 +7,7 @@
 # pypy bundles a modified version of cffi. Use python_gen_cond_dep instead.
 PYTHON_COMPAT=( python2_7 python3_{4,5,6} )
 
-inherit distutils-r1
+inherit distutils-r1 toolchain-funcs
 
 DESCRIPTION="Foreign Function Interface for Python calling C code"
 HOMEPAGE="https://cffi.readthedocs.io/ https://pypi.org/project/cffi/"
@@ -29,6 +29,10 @@
 # Avoid race on _configtest.c (distutils/command/config.py:_gen_temp_sourcefile)
 DISTUTILS_IN_SOURCE_BUILD=1
 
+python_configure_all() {
+	tc-export PKG_CONFIG
+}
+
 python_compile_all() {
 	use doc && emake -C doc html
 }