Bug 988722 - Use buildprops.json to decide whether and how to use sccache. r=bhearsum
Bug 988774 - Do not gracefully disable sccache when it's not there. r=bhearsum
Bug 988168 - Better integrate gtest libxul in the build system. r=mshal

--HG--
rename : toolkit/library/Makefile.in => toolkit/library/libxul.mk
rename : toolkit/library/moz.build => toolkit/library/libxul.mozbuild