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

 # Compute Alpha-specific values

 CT_DoArchTupleValues () {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="${CT_ARCH}${CT_ARCH_SUFFIX:-${CT_ARCH_ALPHA_VARIANT}}"

 }