kbuild: remove the last use of old cmd_src_tar rule in packaging

The rpm-pkg and deb-pkg targets have transitioned to using 'git archive'
for tarball creation.

Although the old cmd_src_tar is still used by snap-pkg, there is no need
to pack and unpack a tarball solely for passing the source to snapcraft.

Instead, you can use 'source-type: local' to tell the source location to
snapcraft.

Signed-off-by: Masahiro Yamada <[e-mail]>

Makefile

···
 export RCS_FIND_IGNORE := \( -name SCCS -o -name BitKeeper -o -name .svn -o    \
 			  -name CVS -o -name .pc -o -name .hg -o -name .git \) \
 			  -prune -o
-export RCS_TAR_IGNORE := --exclude SCCS --exclude BitKeeper --exclude .svn \
-			 --exclude CVS --exclude .pc --exclude .hg --exclude .git
 
 # ===========================================================================
 # Rules shared between *config targets and build targets

scripts/Makefile.package

···
 include $(srctree)/scripts/Kbuild.include
 include $(srctree)/scripts/Makefile.lib
 
-KERNELPATH := kernel-$(subst -,_,$(KERNELRELEASE))
-# Include only those top-level files that are needed by make, plus the GPL copy
-TAR_CONTENT := Documentation LICENSES arch block certs crypto drivers fs \
-               include init io_uring ipc kernel lib mm net rust \
-               samples scripts security sound tools usr virt \
-               .config Makefile \
-               Kbuild Kconfig COPYING $(wildcard localversion*)
-
-quiet_cmd_src_tar = TAR     $(2).tar.gz
-      cmd_src_tar = \
-if test "$(objtree)" != "$(srctree)"; then \
-	echo >&2; \
-	echo >&2 "  ERROR:"; \
-	echo >&2 "  Building source tarball is not possible outside the"; \
-	echo >&2 "  kernel source tree. Don't set KBUILD_OUTPUT"; \
-	echo >&2; \
-	false; \
-fi ; \
-tar -I $(KGZIP) -c $(RCS_TAR_IGNORE) -f $(2).tar.gz \
-	--transform 's:^:$(2)/:S' $(TAR_CONTENT) $(3)
-
 # Git
 # ---------------------------------------------------------------------------
 
···
 	rm -rf $(objtree)/snap
 	mkdir $(objtree)/snap
 	$(MAKE) clean
-	$(call cmd,src_tar,$(KERNELPATH))
 	sed "s@KERNELRELEASE@$(KERNELRELEASE)@; \
-		s@SRCTREE@$(shell realpath $(KERNELPATH).tar.gz)@" \
+		s@SRCTREE@$(abs_srctree)@" \
 		$(srctree)/scripts/package/snapcraft.template > \
 		$(objtree)/snap/snapcraft.yaml
 	cd $(objtree)/snap && \

scripts/package/snapcraft.template

···
   kernel:
     plugin: kernel
     source: SRCTREE
-    source-type: tar
+    source-type: local
     kernel-with-firmware: false