"make valgrind" respects TEST_ARGS environment variable

Author: ajdavis

tests/Makefile.am

@@ -164,7 +164,7 @@ endif
 	done
 
 valgrind: $(TEST_PROGS)
-	$(LIBTOOL) --mode=execute valgrind --leak-check=full --suppressions=$(srcdir)/valgrind.suppressions ./test-libmongoc -f -p
+	$(LIBTOOL) --mode=execute valgrind --leak-check=full --suppressions=$(srcdir)/valgrind.suppressions ./test-libmongoc $(TEST_ARGS)
 
 if OS_LINUX
 abicheck: