st/mesa: fail to alloc a renderbuffer if st_choose_renderbuffer_format fails

This fixes:
  state_tracker/st_format.c:401:st_pipe_format_to_mesa_format:
  Assertion `0' failed.
(cherry picked from commit fb5d9e1199cabe653ae1bb822bb66ce9f0ce7f55)

Conflicts:

	src/mesa/state_tracker/st_cb_fbo.c

1 files changed, 4 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_cb_fbo.c b/src/mesa/state_tracker/st_cb_fbo.c
index 15f8fb31faf..473ed4d9134 100644
--- a/src/mesa/state_tracker/st_cb_fbo.c
+++ b/src/mesa/state_tracker/st_cb_fbo.c
@@ -77,6 +77,10 @@ st_renderbuffer_alloc_storage(struct gl_context * ctx, struct gl_renderbuffer *r
    else
       format = st_choose_renderbuffer_format(screen, internalFormat, rb->NumSamples);
       
+   if (format == PIPE_FORMAT_NONE) {
+      return FALSE;
+   }
+
    /* init renderbuffer fields */
    strb->Base.Width  = width;
    strb->Base.Height = height;