Add PKG_GIT_URL support

diff --git a/config/path b/config/path
index f302c70..fde2e22 100644
--- a/config/path
+++ b/config/path
@@ -61,6 +61,7 @@ SED="sed -i"
   PKG_LICENSE="unknown"
   PKG_SITE=""
   PKG_URL=""
+  PKG_GIT_URL=""
   PKG_SOURCE_NAME=""
   PKG_SOURCE_DIR=""
   PKG_DEPENDS_TARGET=""
@@ -154,6 +155,8 @@ SED="sed -i"
     . $PKG_DIR/package.mk
   fi
 
+  [ -n "$PKG_GIT_URL" -a -z "$PKG_URL" ] && PKG_URL=$PKG_GIT_URL/archive/$PKG_VERSION.tar.gz"
+
   if [ "$PKG_IS_ADDON" = "yes" ] ; then
     [ -z $PKG_SECTION ] && PKG_ADDON_ID="$PKG_NAME" || PKG_ADDON_ID="`echo $PKG_SECTION | sed 's,/,.,g'`.$PKG_NAME"
   fi