[PATCH v4 0/5] Makefile: "make tags" fixes & cleanup

The big win here is that none of the tags targets depend on "FORCE" anymore, so we'll only re-generate them if our sources change.

For v3, see: https://lore.kernel.org/git/cover-0.5-00000000000-20210721T231900Z-avarab@gmail.com/

This addresses the feedback about the cscope* v.s. cscope.out rule in .gitignore and "make clean", i.e. those rules are not being changed anymore. I also changed a stray cscope.out to $@ in 4/5, which was missed in v3.

Ævar Arnfjörð Bjarmason (5):
  Makefile: move ".PHONY: cscope" near its target
  Makefile: add QUIET_GEN to "cscope" target
  Makefile: don't use "FORCE" for tags targets
  Makefile: remove "cscope.out", not "cscope*" in cscope.out target
  Makefile: normalize clobbering & xargs for tags targets

 Makefile | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

Range-diff against v3:
1:  6b4ddc126d9 = 1:  2ee725e2fba Makefile: move ".PHONY: cscope" near its target
2:  d3d5d332e92 = 2:  2122cb25633 Makefile: add QUIET_GEN to "cscope" target
3:  9dd69d68178 = 3:  8649716772b Makefile: don't use "FORCE" for tags targets
4:  f8d151f1f6a ! 4:  643c514e12a Makefile: the "cscope" target always creates a "cscope.out"
    @@ Metadata
     Author: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Commit message ##
    -    Makefile: the "cscope" target always creates a "cscope.out"
    +    Makefile: remove "cscope.out", not "cscope*" in cscope.out target
     
    -    In the preceding commit the "cscope" target was changed to be a phony
    -    alias for the "cscope.out" target.
    +    Before we generate a "cscope.out" file, remove that file explicitly,
    +    and not everything matching "cscope*". This doesn't change any
    +    behavior of the Makefile in practice, but makes this rule less
    +    confusing, and consistent with other similar rules.
     
         The cscope target was added in a2a9150bf06 (makefile: Add a cscope
    -    target, 2007-10-06), and has always referred to cscope* instead of to
    -    cscope.out.
    +    target, 2007-10-06). It has always referred to cscope* instead of to
    +    cscope.out in .gitignore and the "clean" target, even though we only
    +    ever generated a cscope.out file.
     
    -    As far as I can tell this ambiguity was never needed. The
    -    "-fcscope.out" (note, no whitespace) argument is enabled by default,
    -    but let's provide it explicitly for good measure.
    +    This was seemingly done to aid use-cases where someone invoked cscope
    +    with the "-q" flag, which would make it create a "cscope.in.out" and
    +    "cscope.po.out" files in addition to "cscope.out".
     
    -    Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
    +    But us removing those files we never generated is confusing, so let's
    +    only remove the file we need to, furthermore let's use the "-f" flag
    +    to explicitly name the cscope.out file, even though it's the default
    +    if not "-f" argument is supplied.
    +
    +    It is somewhat inconsistent to change from the glob here but not in
    +    the "clean" rule and .gitignore, an earlier version of this change
    +    updated those as well, but see [1][2] for why they were kept.
     
    - ## .gitignore ##
    -@@
    - /.vscode/
    - /tags
    - /TAGS
    --/cscope*
    -+/cscope.out
    - /compile_commands.json
    - *.hcc
    - *.obj
    +    1. https://lore.kernel.org/git/87k0lit57x.fsf@evledraar.gmail.com/
    +    2. https://lore.kernel.org/git/87im0kn983.fsf@evledraar.gmail.com/
    +
    +    Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Makefile ##
     @@ Makefile: tags: $(FOUND_SOURCE_FILES)
    @@ Makefile: tags: $(FOUND_SOURCE_FILES)
      cscope.out: $(FOUND_SOURCE_FILES)
     -	$(QUIET_GEN)$(RM) cscope* && \
     -	echo $(FOUND_SOURCE_FILES) | xargs cscope -b
    -+	$(QUIET_GEN)$(RM) cscope.out && \
    ++	$(QUIET_GEN)$(RM) $@ && \
     +	echo $(FOUND_SOURCE_FILES) | xargs cscope -f$@ -b
      
      .PHONY: cscope
      cscope: cscope.out
    -@@ Makefile: clean: profile-clean coverage-clean cocciclean
    - 	$(RM) $(HCC)
    - 	$(RM) -r bin-wrappers $(dep_dirs) $(compdb_dir) compile_commands.json
    - 	$(RM) -r po/build/
    --	$(RM) *.pyc *.pyo */*.pyc */*.pyo $(GENERATED_H) $(ETAGS_TARGET) tags cscope*
    -+	$(RM) *.pyc *.pyo */*.pyc */*.pyo $(GENERATED_H) $(ETAGS_TARGET) tags cscope.out
    - 	$(RM) -r .dist-tmp-dir .doc-tmp-dir
    - 	$(RM) $(GIT_TARNAME).tar.gz
    - 	$(RM) $(htmldocs).tar.gz $(manpages).tar.gz
5:  f3ff76d0e98 ! 5:  1eaf3416329 Makefile: normalize clobbering & xargs for tags targets
    @@ Makefile: FIND_SOURCE_FILES = ( \
     +	mv $@+ $@
      
      cscope.out: $(FOUND_SOURCE_FILES)
    --	$(QUIET_GEN)$(RM) cscope.out && \
    +-	$(QUIET_GEN)$(RM) $@ && \
     -	echo $(FOUND_SOURCE_FILES) | xargs cscope -f$@ -b
     +	$(QUIET_GEN)$(RM) $@+ && \
     +	echo $(FOUND_SOURCE_FILES) | xargs cscope -f$@+ -b && \