package/php-xdebug: drop unrecognized variable

--with-xdebug is not recognized since the addition of the package in
commit 7b7dffd0984e1b274273f5638a975165606384f9:

configure: WARNING: unrecognized options: --disable-gtk-doc, --disable-gtk-doc-html, --disable-doc, --disable-docs, --disable-documentation, --with-xmlto, --with-fop, --disable-dependency-tracking, --enable-ipv6, --disable-nls, --with-xdebug

Fixes: 7b7dffd0984e1b274273f5638a975165606384f9

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 98ee9f8b49ebd7aa6d9dc2c726030ec396910f6c)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/php-xdebug/php-xdebug.mk

@@ -14,8 +14,7 @@ PHP_XDEBUG_LICENSE_FILES = LICENSE
 PHP_XDEBUG_DEPENDENCIES = php host-autoconf
 PHP_XDEBUG_CONF_OPTS = \
 	--enable-xdebug \
-	--with-php-config=$(STAGING_DIR)/usr/bin/php-config \
-	--with-xdebug=$(STAGING_DIR)/usr
+	--with-php-config=$(STAGING_DIR)/usr/bin/php-config
 
 define PHP_XDEBUG_PHPIZE
 	(cd $(@D); \