vrend: enable multisample on GLES host with GLES >= 3.0

Multisample fragment operations are part of the OpenGL ES 3.0 spec and
enabling them doesn't required the extensions to be listed explicitly.

Fixes:

 dEQP-GLES3.functional.multisample.fbo_max_samples.proportionality_alpha_to_coverage
 dEQP-GLES3.functional.multisample.fbo_max_samples.proportionality_sample_coverage
 dEQP-GLES3.functional.multisample.fbo_max_samples.proportionality_sample_coverage_inverted
 dEQP-GLES3.functional.multisample.fbo_max_samples.sample_coverage_invert

on an GLES host with GLES >= 3.0.

v2: - Do not set GL_SAMPLE_ALPHA_TO_ONE state when on gles host, because it is
      not supported there. This silences a number of according warnings on the
      host.

v3: - Properly place if statement to not send GL_SAMPLE_ALPHA_TO_ONE.
    - Do not set GL_MULTISAMPLE state when on gles host (same as above).

v4: - fix nitpicks in commit message

v5: - seperate setting of GL_MULTISAMPLE (not available on GLES) and
      GL_SAMPLES_TEST

Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Signed-off-by: Jakob Bornecrantz <jakob@collabora.com>

src/vrend_renderer.c

@@ -3374,10 +3374,12 @@ static void vrend_hw_emit_blend(struct vrend_context *ctx, struct pipe_blend_sta
       else
          glDisable(GL_SAMPLE_ALPHA_TO_COVERAGE);
 
-      if (state->alpha_to_one)
-         glEnable(GL_SAMPLE_ALPHA_TO_ONE);
-      else
-         glDisable(GL_SAMPLE_ALPHA_TO_ONE);
+      if (!vrend_state.use_gles) {
+         if (state->alpha_to_one)
+            glEnable(GL_SAMPLE_ALPHA_TO_ONE);
+         else
+            glDisable(GL_SAMPLE_ALPHA_TO_ONE);
+      }
    }
 
    if (state->dither)
@@ -3817,13 +3819,19 @@ static void vrend_hw_emit_rs(struct vrend_context *ctx)
    }
 
    if (vrend_state.have_multisample) {
-      if (state->multisample) {
-         glEnable(GL_MULTISAMPLE);
+      if (state->multisample)
          glEnable(GL_SAMPLE_MASK);
-      } else {
-         glDisable(GL_MULTISAMPLE);
+      else
          glDisable(GL_SAMPLE_MASK);
+
+      /* GLES doesn't have GL_MULTISAMPLE */
+      if (!vrend_state.use_gles) {
+         if (state->multisample)
+            glEnable(GL_MULTISAMPLE);
+         else
+            glDisable(GL_MULTISAMPLE);
       }
+
       if (vrend_state.have_sample_shading) {
          if (state->force_persample_interp)
             glEnable(GL_SAMPLE_SHADING);
@@ -4248,7 +4256,9 @@ int vrend_renderer_init(struct vrend_if_cbs *cbs, uint32_t flags)
 
    if (epoxy_has_gl_extension("GL_ARB_stencil_texturing"))
       vrend_state.have_stencil_texturing = true;
-   if (epoxy_has_gl_extension("GL_EXT_framebuffer_multisample") && epoxy_has_gl_extension("GL_ARB_texture_multisample")) {
+   if ((gles && gl_ver >= 30) ||
+       (epoxy_has_gl_extension("GL_EXT_framebuffer_multisample") &&
+        epoxy_has_gl_extension("GL_ARB_texture_multisample"))) {
       vrend_state.have_multisample = true;
       if (epoxy_has_gl_extension("GL_EXT_framebuffer_multisample_blit_scaled"))
          vrend_state.have_ms_scaled_blit = true;