test/run-make: another missing $(EXTRACFLAGS).

rust-lang/rust@102b1a5bf1a60eeafb752844e5c98fe5f4e3b992 was not enough!

Signed-off-by: NODA, Kai <nodakai@gmail.com>
auto merge of #19443 : nodakai/rust/another-missing-extracflags, r=alexcrichton

rust-lang/rust@102b1a5bf1a60eeafb752844e5c98fe5f4e3b992 was not enough!