kbuild: pacman-pkg: do not override objtree

objtree is defined and exported by the top-level Makefile. I prefer
not to override it.

There is no need to pass the absolute path of objtree. PKGBUILD can
detect it by itself.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by:  Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Christian Heusel <christian@heusel.eu>

scripts/package/PKGBUILD

@@ -40,7 +40,9 @@ _prologue() {
 	# MAKEFLAGS from makepkg.conf override the ones inherited from kbuild.
 	# Bypass this override with a custom variable.
 	export MAKEFLAGS="${KBUILD_MAKEFLAGS}"
-	cd "${objtree}"
+
+	# Kbuild works in the output directory, where this PKGBUILD is located.
+	cd "$(dirname "${BASH_SOURCE[0]}")"
 }
 
 build() {