Fixed the issue that dirname: META got zipped twice.

When building target-files-package, dir: META has to be copied first
to help early validation of the .zip file.

In order to prevent $(zip_root)/META from getting copied twice to $@.list,
use the method (find -path -prune -o -print) instead of (grep pattern -v).

Test: m target-files-package
Bug: b/31676493
Change-Id: Id6b4d77fb62aa136253de88573cc51a575b90be2
diff --git a/core/Makefile b/core/Makefile
index cf0aa4a..0dd5098 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -2161,7 +2161,7 @@
 	@# Zip everything up, preserving symlinks and placing META/ files first to
 	@# help early validation of the .zip file while uploading it.
 	$(hide) find $(zip_root)/META | sort >$@.list
-	$(hide) find $(zip_root) | grep -v "^$(zip_root)/META/" | sort >>$@.list
+	$(hide) find $(zip_root) -path $(zip_root)/META -prune -o -print | sort >>$@.list
 	$(hide) $(SOONG_ZIP) -d -o $@ -C $(zip_root) -l $@.list
 
 .PHONY: target-files-package