Add goma=on option to Makefile build.

Makefile

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 144 matching lines @@
 ifeq ($(asan), on)
   GYPFLAGS += -Dasan=1 -Dclang=1
   TESTFLAGS += --asan
   ifeq ($(lsan), on)
     GYPFLAGS += -Dlsan=1
   endif
 endif
 ifdef embedscript
   GYPFLAGS += -Dembed_script=$(embedscript)
 endif
-
+ifeq ($(use_goma), on)

[Michael Achenbach, 2015/07/09 08:11:20]

how about just goma=on?

+  GYPFLAGS += -Duse_goma=1
+endif
 # arm specific flags.
 # arm_version=<number | "default">
 ifneq ($(strip $(arm_version)),)
   GYPFLAGS += -Darm_version=$(arm_version)
 else
 # Deprecated (use arm_version instead): armv7=false/true
 ifeq ($(armv7), false)
   GYPFLAGS += -Darm_version=6
 else
 ifeq ($(armv7), true)
@@ skipping 312 matching lines @@
 # We need to manually set the stack limit here, to work around bugs in
 # gmake-3.81 and global-5.7.1 on recent 64-bit Linux systems.
 GPATH GRTAGS GSYMS GTAGS: gtags.files $(shell cat gtags.files 2> /dev/null)
         @bash -c 'ulimit -s 10240 && GTAGSFORCECPP=yes gtags -i -q -f $<'
 
 gtags.clean:
         rm -f gtags.files GPATH GRTAGS GSYMS GTAGS
 
 dependencies builddeps:
         $(error Use 'gclient sync' instead)