Export error reporting function to allow using it in other packages.

Test: lunch aosp_cf_x86_phone-userdebug && m
Change-Id: I3a1d936ac57966b2f47cb1d9a56e0f96f47b807d
diff --git a/android/module.go b/android/module.go
index b689a87..17bc205 100644
--- a/android/module.go
+++ b/android/module.go
@@ -2246,7 +2246,7 @@
 		return nil
 	}
 	if len(paths) > 1 {
-		reportPathErrorf(ctx, "got multiple output files from module %q, expected exactly one",
+		ReportPathErrorf(ctx, "got multiple output files from module %q, expected exactly one",
 			pathContextName(ctx, module))
 		return nil
 	}