kbuild: move kbuild syntax processing to scripts/Makefile.build
scripts/Makefile.lib is included by the following Makefiles:
scripts/Makefile.build
scripts/Makefile.modfinal
scripts/Makefile.package
scripts/Makefile.vmlinux
scripts/Makefile.vmlinux_o
However, the last four do not need to process Kbuild syntax such as
obj-*, lib-*, subdir-*, etc.
Move the relevant code to scripts/Makefile.build.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas.schier@linux.dev>