Don't concatenate the NOTICE file for a single module.

When the NOTICE file for a module changed, the new NOTICE was being
concatenated onto the end of the old one in non-clean builds, taking up
more and more space and presumably duplicating most of the content. Only
one set of rules for a given file can exist in make, so there cannot be
a case where more than one $(notice_file) was intentionally being
concatenated together as this would be an error.

Change-Id: I0f5fae498225eaee5cc75d854223b5ba790fcebe
diff --git a/core/notice_files.mk b/core/notice_files.mk
index 2c0a3d3..7e61c1e 100644
--- a/core/notice_files.mk
+++ b/core/notice_files.mk
@@ -64,7 +64,7 @@
 $(installed_notice_file): $(notice_file)
 	@echo Notice file: $< -- $@
 	$(hide) mkdir -p $(dir $@)
-	$(hide) cat $< >> $@
+	$(hide) cat $< > $@
 
 ifdef LOCAL_INSTALLED_MODULE
 # Make LOCAL_INSTALLED_MODULE depend on NOTICE files if they exist