Add some initial benchmarking for bp2build.

Test: go test -benchmark=. in bp2build directory
Change-Id: I8275c38461078cc6100fbc89837177de0edc9d68
diff --git a/bp2build/Android.bp b/bp2build/Android.bp
index 9ec637a..78e3a74 100644
--- a/bp2build/Android.bp
+++ b/bp2build/Android.bp
@@ -39,6 +39,7 @@
         "cc_library_static_conversion_test.go",
         "cc_object_conversion_test.go",
         "conversion_test.go",
+        "performance_test.go",
         "prebuilt_etc_conversion_test.go",
         "python_binary_conversion_test.go",
         "sh_conversion_test.go",