gallium/util: Implement util_format_is_etc

This is the equivalent of util_format_is_s3tc, but for ETC.

Signed-off-by: Wladimir J. van der Laan <laanwj@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

src/gallium/auxiliary/util/u_format.h

@@ -495,6 +495,19 @@ util_format_is_s3tc(enum pipe_format format)
    return desc->layout == UTIL_FORMAT_LAYOUT_S3TC ? TRUE : FALSE;
 }
 
+static inline boolean
+util_format_is_etc(enum pipe_format format)
+{
+   const struct util_format_description *desc = util_format_description(format);
+
+   assert(desc);
+   if (!desc) {
+      return FALSE;
+   }
+
+   return desc->layout == UTIL_FORMAT_LAYOUT_ETC ? TRUE : FALSE;
+}
+
 static inline boolean 
 util_format_is_srgb(enum pipe_format format)
 {