[gtk/wip/chergert/glproto] ignore unused uniforms in gl shader

[Christian Hergert <chergert src gnome org>]

commit df2d92b63acfecc827eb5f7b956ad7a94ea502c3
Author: Christian Hergert <chergert redhat com>
Date:   Wed Feb 17 07:52:07 2021 -0800

    ignore unused uniforms in gl shader

 gsk/next/gskglrenderjob.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/gsk/next/gskglrenderjob.c b/gsk/next/gskglrenderjob.c
index c03cb71921..29d427b57f 100644
--- a/gsk/next/gskglrenderjob.c
+++ b/gsk/next/gskglrenderjob.c
@@ -3008,6 +3008,10 @@ gsk_gl_render_job_visit_gl_shader_node (GskGLRenderJob      *job,
           const GskGLUniform *u = &uniforms[i];
           const guint8 *data = base + u->offset;
 
+          /* Ignore unused uniforms */
+          if (program->args_locations[i] == -1)
+            continue;
+
           switch (u->type)
             {
             default: