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

diff --cc Makefile
Simple merge