Print an error if idling the engine before the buffer copy fails.

Be a bit more useful about the sync message after flushing command buffers.

Add an "allmsg" debug name that enables all log messages but does not
enable syncing.

src/mesa/drivers/dri/r300/r300_cmdbuf.c

@@ -96,7 +96,7 @@ int r300FlushCmdBufLocked(r300ContextPtr r300, const char* caller)
 			DRM_RADEON_CMDBUF, &cmd, sizeof(cmd));
 
 	if (RADEON_DEBUG & DEBUG_SYNC) {
-		fprintf(stderr, "Syncing in %s\n\n", __FUNCTION__);
+		fprintf(stderr, "Syncing in %s (from %s)\n\n", __FUNCTION__, caller);
 		radeonWaitForIdleLocked(&r300->radeon);
 	}
 

src/mesa/drivers/dri/r300/radeon_screen.c

@@ -149,6 +149,7 @@ static const struct dri_debug_control debug_control[] = {
 	{"sync", DEBUG_SYNC},
 	{"pix", DEBUG_PIXEL},
 	{"mem", DEBUG_MEMORY},
+	{"allmsg", ~DEBUG_SYNC}, /* avoid the term "sync" because the parser uses strstr */
 	{NULL, 0}
 };