The binary constant notation "0b" is a GCC extension. Instead, we use
hexadecimal notation to fix the MSVC 2013 build:

Compiling src\mesa\main\texcompress_astc.cpp ...
texcompress_astc.cpp
src\mesa\main\texcompress_astc.cpp(111) : error C2059: syntax error : 'bad suffix on number'

...

src\mesa\main\texcompress_astc.cpp(1007) : fatal error C1003: error count exceeds 100; stopping compilation
scons: *** [build\windows-x86-debug\mesa\main\texcompress_astc.obj] Error 2
scons: building terminated because of errors.

v2: Fix wrong conversion (Ilia).

Fixes: 38ab39f6

 ("mesa: add ASTC 2D LDR decoder")
Cc: Marek Olšák <marek.olsak@amd.com>
Cc: Brian Paul <brianp@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: Mike Lothian <mike@fireburn.co.uk>
Cc: Gert Wollny <gert.wollny@collabora.com>
Cc: Dieter Nützel <Dieter@nuetzel-hh.de>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Andres Gomez <agomez@igalia.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>