Makefiles need to be indented by tabs

Makefile.in

@@ -1,3 +1,5 @@
+# -*- mode: makefile-gmake; indent-tabs-mode: t -*-
+
 SHELL = /bin/sh
 NULLCMD = @NULLCMD@
 n=$(NULLCMD)

common.mk

@@ -1,3 +1,5 @@
+# -*- mode: makefile-gmake; indent-tabs-mode: t -*-
+
 bin: $(PROGRAM) $(WPROGRAM)
 lib: $(LIBRUBY)
 dll: $(LIBRUBY_SO)

defs/gmake.mk

@@ -1,4 +1,5 @@
-# -*- makefile-gmake -*-
+# -*- mode: makefile-gmake; indent-tabs-mode: t -*-
+
 gnumake = yes
 override gnumake_recursive := $(if $(findstring n,$(firstword $(MFLAGS))),,+)
 override mflags := $(filter-out -j%,$(MFLAGS))

win32/Makefile.sub

@@ -1,4 +1,4 @@
-# -*- makefile -*-
+# -*- mode: makefile; indent-tabs-mode: t -*-
 
 SHELL = $(COMSPEC)
 ECHO1 = $(V:1=@:)