Add support for .proto files

.proto files are translated to .pb.cc and .pb.h files, which are then
compiled normally.

Bug: 32286026
Test: mmma -j system/extras/perfprofd
Change-Id: I538071424d667aacf35b4b8bfebe217f5f092726
diff --git a/Android.bp b/Android.bp
index 8821098..f9ba2c2 100644
--- a/Android.bp
+++ b/Android.bp
@@ -129,6 +129,7 @@
         "cc/gen.go",
         "cc/makevars.go",
         "cc/prebuilt.go",
+        "cc/proto.go",
         "cc/relocation_packer.go",
         "cc/sanitize.go",
         "cc/stl.go",