Use --libdir=/usr/lib32 on x86 and create/remove the symlink via hooks.

This is to make all pkgs that use ${configure_args} work without changes
to the templates on x86_64.

common/hooks/pre-install/00-lib32.sh

@@ -0,0 +1,8 @@
+# This hook creates the /usr/lib32 symlink for x86.
+
+hook() {
+	if [ "$XBPS_TARGET_MACHINE" = "i686" ]; then
+		vmkdir usr/lib
+		ln -sf lib ${DESTDIR}/usr/lib32
+	fi
+}