versioner: compile headers in both C and C++ mode.

Bug: https://github.com/android-ndk/ndk/issues/440
Test: python run_tests.py
Change-Id: Ib572a8fdcc00f6b88a25003a085b16ce9698d692
diff --git a/tools/versioner/tests/unnamed_bitfield/headers/foo.h b/tools/versioner/tests/unnamed_bitfield/headers/foo.h
new file mode 100644
index 0000000..58686c3
--- /dev/null
+++ b/tools/versioner/tests/unnamed_bitfield/headers/foo.h
@@ -0,0 +1,8 @@
+// <sys/timex.h> was causing a segfault when compiled in C++ mode because
+// versioner was trying to mangle the name of an unnamed bitfield.
+struct foo {
+  int : 32;
+  int : 32;
+  int : 32;
+  int : 32;
+};