[#17433] Cannot break node links with LMB drag under linux.

Grease pencil commit added some panel draw code or whatnot which seems to change the matrix stack in unwanted (in this case) ways. Reset to identity fixes it.

* I don't think it was limited to Linux though

source/blender/src/editnode.c

@@ -2110,6 +2110,7 @@ static void node_border_link_delete(SpaceNode *snode)
 			mval[1]= rect.ymax;
 			areamouseco_to_ipoco(&snode->v2d, mval, &rectf.xmax, &rectf.ymax);
 			
+			glLoadIdentity();
 			myortho2(rectf.xmin, rectf.xmax, rectf.ymin, rectf.ymax);
 			
 			glSelectBuffer(256, buffer);