Merge branch 'tip/perf/core-2' of...

	@echo  '  make O=dir [targets] Locate all output files in "dir", including .config'

	@echo  '  make C=1   [targets] Check all c source with $$CHECK (sparse by default)'

	@echo  '  make C=2   [targets] Force check of all c source with $$CHECK'

	@echo  '  make RECORDMCOUNT_WARN=1 [targets] Warn about ignored mcount sections'

	@echo  '  make W=n   [targets] Enable extra gcc checks, n=1,2,3 where'

	@echo  '		1: warnings which may be relevant and do not occur too often'

	@echo  '		2: warnings which occur quite often but may still be relevant'