x11r7/libXext: use install-strip for target install

Saves ~400 KB

package/x11r7/xlib_libXext/xlib_libXext.mk

@@ -9,6 +9,8 @@ XLIB_LIBXEXT_SOURCE = libXext-$(XLIB_LIBXEXT_VERSION).tar.bz2
 XLIB_LIBXEXT_SITE = http://xorg.freedesktop.org/releases/individual/lib
 XLIB_LIBXEXT_AUTORECONF = NO
 XLIB_LIBXEXT_INSTALL_STAGING = YES
+XLIB_LIBXEXT_INSTALL_TARGET = YES
+XLIB_LIBXEXT_INSTALL_TARGET_OPT = DESTDIR=$(TARGET_DIR) install-strip
 XLIB_LIBXEXT_DEPENDENCIES = xlib_libX11 xproto_xextproto xproto_xproto
 XLIB_LIBXEXT_CONF_OPT = --disable-malloc0returnsnull --enable-shared --disable-static