gpu: Take color state into account for glyph lookup

Add a 'linear' bit to the glyph cache key, so we can get have
separate cached images for the two cases. Note that the image
tagging with color state is ignored here - we simply copy the
glyph image out of the atlas as-is, and rely on the cache to
give use the right color state.

gsk/gpu/gskgpudevice.c

@@ -977,6 +977,7 @@ gsk_gpu_device_lookup_glyph_image (GskGpuDevice           *self,
 
   gsk_gpu_upload_glyph_op (frame,
                            cache->image,
+                           (flags & GSK_GPU_GLYPH_LINEAR) != 0,
                            scaled_font,
                            glyph,
                            &(cairo_rectangle_int_t) {

gsk/gpu/gskgpudeviceprivate.h

@@ -88,7 +88,8 @@ typedef enum
   GSK_GPU_GLYPH_X_OFFSET_3 = 0x3,
   GSK_GPU_GLYPH_Y_OFFSET_1 = 0x4,
   GSK_GPU_GLYPH_Y_OFFSET_2 = 0x8,
-  GSK_GPU_GLYPH_Y_OFFSET_3 = 0xC
+  GSK_GPU_GLYPH_Y_OFFSET_3 = 0xC,
+  GSK_GPU_GLYPH_LINEAR = 0x10,
 } GskGpuGlyphLookupFlags;
 
 GskGpuImage *           gsk_gpu_device_lookup_glyph_image               (GskGpuDevice           *self,

gsk/gpu/gskgpunodeprocessor.c

@@ -3185,6 +3185,9 @@ gsk_gpu_node_processor_add_glyph_node (GskGpuNodeProcessor *self,
       glyph_origin.x *= inv_align_scale_x;
       glyph_origin.y *= inv_align_scale_y;
 
+      if (gdk_color_state_is_linear (self->color_state))
+        flags |= GSK_GPU_GLYPH_LINEAR;
+
       image = gsk_gpu_device_lookup_glyph_image (device,
                                                  self->frame,
                                                  font,