Mask C and C++ files.

These files are only required at build time.

BUG=chromium:417132
TEST=`./build_image` doesn't have these files.

Change-Id: I8fc91686b64571566e743eb5767c1b8ba007e6b1
Reviewed-on: https://chromium-review.googlesource.com/219683
Reviewed-by: Gaurav Shah <gauravsh@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
diff --git a/common.sh b/common.sh
index 16edd71..68916d1 100644
--- a/common.sh
+++ b/common.sh
@@ -393,6 +393,8 @@
 # TODO: Is /usr/local/autotest-chrome still used by anyone?
 COMMON_INSTALL_MASK="
   *.a
+  *.c
+  *.cc
   *.la
   *.h
   *.hpp