cc/gcc: fix gcc 4.8 build for C library without threads support

Signed-off-by: Niels Penneman <niels@penneman.org>
Message-Id: <309df93f4354c80e05c9.1388743085@i7sb.local>
Patchwork-Id: 306521

 reporter_name="Ioannis E. Venetis"

 reporter_url="http://sourceware.org/ml/crossgcc/2011-05/msg00005.html"

 reporter_comment=""