sb-concurrency fails self-tests on Windows

[slaguth]

The sb-concurrency contrib started failing its self-tests some time after 1.1.4 and before 1.1.5. See the attached file for a demonstration of the failure on 1.1.5. This failure has been reproduced successfully for every single release since 1.1.5, including 1.1.6, 1.1.7, and 1.1.8.

Build configuration:
SBCL versions > 1.1.4 and <= 1.1.8
Windows 7 (fully upgraded at the time of build)
both x86 and x86-64
MinGW

$ uname -a
MINGW32_NT-6.1 BLACKTHORN 1.0.17(0.48/3/2) 2011-04-24 23:39 i686 Msys

$ gcc --version
gcc.exe (GCC) 4.7.0

[Stas Boukarev (stassats)]

Seems to be not failing anymore.