[PATCH] Makefile: add help target

[Elia Pinto <gitter.spiros@gmail.com>]

Add a help target to the Makefile to be able to run make help, in the same way
does the Makefiles self-generated by some build systems.

The target list has been statically extracted from the git Makefile with a
script and the results have been filtered in an essentially arbitrary way to
leave the ones that i imagines most interesting and frequent for a developer.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
---
The toy script I used is here
https://gist.github.com/devzero2000/cb887a6ba2764f7234191e560b64b7c8#file-list_targets_makefile-sh
 Makefile | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/Makefile b/Makefile
index e8aba291d7..f6d6de2eb9 100644
--- a/Makefile
+++ b/Makefile
@@ -3448,3 +3448,66 @@ $(FUZZ_PROGRAMS): all
 		$(XDIFF_OBJS) $(EXTLIBS) git.o $@.o $(LIB_FUZZING_ENGINE) -o $@
 
 fuzz-all: $(FUZZ_PROGRAMS)
+
+# Help Target
+help:
+	@echo "The following are some of the valid targets for this Makefile:"
+	@echo "... all (the default if no target is provided)"
+	@echo "... build-perl-script"
+	@echo "... build-python-script"
+	@echo "... build-sh-script"
+	@echo "... check"
+	@echo "... check-builtins"
+	@echo "... check-docs"
+	@echo "... check-sha1"
+	@echo "... clean"
+	@echo "... clean-perl-script"
+	@echo "... clean-python-script"
+	@echo "... clean-sh-script"
+	@echo "... coccicheck"
+	@echo "... coccicheck-pending"
+	@echo "... cocciclean"
+	@echo "... configure"
+	@echo "... coverage"
+	@echo "... coverage-clean"
+	@echo "... coverage-clean-results"
+	@echo "... coverage-compile"
+	@echo "... coverage-prove"
+	@echo "... coverage-report"
+	@echo "... coverage-test"
+	@echo "... coverage-untested-functions"
+	@echo "... cover_db"
+	@echo "... cover_db_html"
+	@echo "... cscope"
+	@echo "... dist"
+	@echo "... distclean"
+	@echo "... dist-doc"
+	@echo "... doc"
+	@echo "... fuzz-all"
+	@echo "... fuzz-commit-graph"
+	@echo "... fuzz-objs"
+	@echo "... fuzz-pack-headers"
+	@echo "... fuzz-pack-idx"
+	@echo "... html"
+	@echo "... info"
+	@echo "... install"
+	@echo "... man"
+	@echo "... pdf"
+	@echo "... perf"
+	@echo "... profile"
+	@echo "... profile-clean"
+	@echo "... profile-fast"
+	@echo "... profile-fast-install"
+	@echo "... profile-install"
+	@echo "... quick-install-doc"
+	@echo "... quick-install-html"
+	@echo "... quick-install-man"
+	@echo "... reconfigure"
+	@echo "... rpm"
+	@echo "... sparse"
+	@echo "... strip"
+	@echo "... style"
+	@echo "... tags"
+	@echo "... TAGS"
+	@echo "... test"
+.PHONY : help
-- 
2.35.1