Set mode for GNU Makefile.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41491 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

defs/gmake.mk

@@ -1,3 +1,4 @@
+# -*- makefile-gmake -*-
 TEST_TARGETS := $(filter check test check% test% btest%,$(MAKECMDGOALS))
 TEST_TARGETS += $(subst check,test-all,$(patsubst check-%,test-%,$(TEST_TARGETS)))
 TEST_TARGETS := $(patsubst test-%,yes-test-%,$(patsubst btest-%,yes-btest-%,$(TEST_TARGETS)))