Merge branch 'ab/make-tags-cleanup'

Build clean-up for "make tags" and friends. * ab/make-tags-cleanup: Makefile: normalize clobbering & xargs for tags targets Makefile: remove "cscope.out", not "cscope*" in cscope.out target Makefile: don't use "FORCE" for tags targets Makefile: add QUIET_GEN to "cscope" target Makefile: move ".PHONY: cscope" near its target