common/hooks/{pre,post}-install: generalized libdir hook

this makes sure we don't have to worry about packages installing
stuff in lib32/lib64, it will be automagically symlinked

if something is still left over for whatever reason, or if the
opposite wordsize directory exists, that will be caught by pkglint

common/hooks/post-install/00-libdir.sh

@@ -0,0 +1,7 @@
+# This hook removes the wordsize specific libdir symlink.
+
+hook() {
+	if [ "${pkgname}" != "base-files" ]; then
+		rm -f ${PKGDESTDIR}/usr/lib${XBPS_TARGET_WORDSIZE}
+	fi
+}