Add cc_genrule

cc_genrule is the same as a normal genrule, but can depend on other cc
modules (like cc_object).

Test: mmma external/minijail
Change-Id: I8df87665c7bdc76ce89c92755c054f967a818e57
diff --git a/Android.bp b/Android.bp
index 0875a2b..1f45e7a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -150,6 +150,8 @@
         "cc/llndk_library.go",
 
         "cc/kernel_headers.go",
+
+        "cc/genrule.go",
     ],
     testSrcs: [
         "cc/cc_test.go",