vrend: Cleanup use of glBindFragDataLocationIndexed

With GLES we always set the correct binding if dual source blend
is disabled, with OpenGL we still have to do this to handle outputs
that might be optimized away.

v2: Fix comment (Yiwei Zhang)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Yiwei Zhang <zzyiwei@chromium.org>

src/vrend_renderer.c

@@ -1667,19 +1667,16 @@ static struct vrend_linked_shader_program *add_shader_program(struct vrend_sub_c
          } else {
             vrend_report_context_error(sub_ctx->parent, VIRGL_ERROR_CTX_ILLEGAL_DUAL_SRC_BLEND, 0);
          }
-      } else if (has_feature(feat_dual_src_blend)) {
+      } else if (!vrend_state.use_gles && has_feature(feat_dual_src_blend)) {
+         /* On GLES without dual source blending we emit the layout directly in the shader
+          * so there is no need to define the binding here */
          for (int i = 0; i < fs->sel->sinfo.num_outputs; ++i) {
             if (fs->sel->sinfo.fs_output_layout[i] >= 0) {
                char buf[64];
                snprintf(buf, sizeof(buf), "fsout_c%d", fs->sel->sinfo.fs_output_layout[i]);
-               if (!vrend_state.use_gles)
                glBindFragDataLocationIndexed(prog_id, fs->sel->sinfo.fs_output_layout[i], 0, buf);
-               else
-                  glBindFragDataLocationIndexedEXT(prog_id, fs->sel->sinfo.fs_output_layout[i], 0, buf);
             }
          }
-      } else {
-         vrend_report_context_error(sub_ctx->parent, VIRGL_ERROR_CTX_UNSUPPORTED_FUNCTION, 0);
       }
    } else
       sprog->dual_src_linked = false;