libecore: x-includes and x-libraries must be set for cross-compiling

If those flags are not explicitly passed, the libecore configure
script will include -I/usr/X11R6/include and -L/usr/X11R6/lib in the
compile flags, which are obviously unsafe for cross-compilation.

The fix is similar to "package/efl/libevas: x-includes and x-libraries
must be set for cross-compiling" done by Romain Naour on libecore.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/efl/libecore/libecore.mk

@@ -74,7 +74,10 @@ LIBECORE_CONF_OPTS += --disable-ecore-sdl
 endif
 
 ifeq ($(BR2_PACKAGE_LIBECORE_X),y)
-LIBECORE_CONF_OPTS += --enable-ecore-x
+LIBECORE_CONF_OPTS += --enable-ecore-x \
+	--with-x=$(STAGING_DIR) \
+	--x-includes=$(STAGING_DIR)/usr/include \
+	--x-libraries=$(STAGING_DIR)/usr/lib
 LIBECORE_DEPENDENCIES += xlib_libXext xlib_libX11
 else
 LIBECORE_CONF_OPTS += --disable-ecore-x --disable-ecore-imf-xim