THRIFT-4717: fix up make clean with autoconf
diff --git a/lib/php/test/Makefile.am b/lib/php/test/Makefile.am
index 4824688..6f4e50a 100755
--- a/lib/php/test/Makefile.am
+++ b/lib/php/test/Makefile.am
@@ -48,6 +48,8 @@
   check-validator \
   check-json-serializer
 
+distclean-local:
+
 clean-local:
 	$(RM) -r ./packages
 	$(RM) TEST-*.xml