Add nanopb-c support

Test: cd hardware/ril; mma
Change-Id: Id1481940d15a2a3f6eb29af54ee30080ff2286cb
diff --git a/cc/gen.go b/cc/gen.go
index 29a2bb2..4852794 100644
--- a/cc/gen.go
+++ b/cc/gen.go
@@ -182,8 +182,7 @@
 			srcFiles[i] = cppFile
 			genLex(ctx, srcFile, cppFile)
 		case ".proto":
-			ccFile, headerFile := genProto(ctx, srcFile, buildFlags.protoFlags,
-				buildFlags.protoOutParams, buildFlags.protoRoot)
+			ccFile, headerFile := genProto(ctx, srcFile, buildFlags)
 			srcFiles[i] = ccFile
 			deps = append(deps, headerFile)
 		case ".aidl":