Fix regression with incremental snap in Graph Editor

Regression introduced in {rBb0d9e6797fb8}.

Previously the Graphics Editor had a conflict with two different snap
types. Auto-Snap and Snap with Ctrl.

It is now clearer which snap should prevail.

source/blender/editors/transform/transform_snap.c

@@ -615,7 +615,7 @@ static void initSnappingMode(TransInfo *t)
       t->tsnap.mode |= SCE_SNAP_MODE_GRID;
     }
   }
-  else if (ELEM(t->spacetype, SPACE_GRAPH, SPACE_ACTION, SPACE_NLA)) {
+  else if (ELEM(t->spacetype, SPACE_ACTION, SPACE_NLA)) {
     /* No incremental snapping. */
     t->tsnap.mode = 0;
   }

source/blender/editors/transform/transform_snap_animation.c

@@ -56,12 +56,17 @@ short getAnimEdit_SnapMode(TransInfo *t)
     }
   }
   else if (t->spacetype == SPACE_GRAPH) {
+    if ((t->data_type == TFM_TRANSLATION) && activeSnap(t)) {
+      /* Use the translate mode snap. */
+    }
+    else {
       SpaceGraph *sipo = (SpaceGraph *)t->area->spacedata.first;
 
       if (sipo) {
         autosnap = sipo->autosnap;
       }
     }
+  }
   else if (t->spacetype == SPACE_NLA) {
     SpaceNla *snla = (SpaceNla *)t->area->spacedata.first;