Per skip's email:
FWIW, it appears that Solaris doesn't define SEM_VALUE_MAX but does 
define
_SEM_VALUE_MAX in sys/params.h.

   .../Modules/_multiprocessing/multiprocessing.c: In function 
'init_multiprocessing':
   .../Modules/_multiprocessing/multiprocessing.c:253: error: 
'SEM_VALUE_MAX' undeclared (first use in this function)
   .../Modules/_multiprocessing/multiprocessing.c:253: error: (Each 
undeclared identifier is reported only once
   .../Modules/_multiprocessing/multiprocessing.c:253: error: for each 
function it appears in.)

On Windows the author simple #defines SEM_VALUE_MAX to be LONG_MAX.  I 
used
a little cpp action to define it:

   #ifndef SEM_VALUE_MAX
   #  ifdef _SEM_VALUE_MAX
   #    define SEM_VALUE_MAX _SEM_VALUE_MAX
   #  else
   #    define SEM_VALUE_MAX INT_MAX
   #  endif
   #endif