Howto build libpq.dll using VC2003 and ENABLE_THREAD_SAFETY=1

Building without ENABLE_THREAD_SAFETY=1 works fine, but when i add this
option to the win32.mak some compiler error occur.

d:\postgresql-8.0.3\src\interfaces\libpq\libpq-int.h(481) : error
C2143: syntax error : missing ')' before '*'
d:\postgresql-8.0.3\src\interfaces\libpq\libpq-int.h(481) : error
C2143: syntax error : missing '{' before '*'
d:\\postgresql-8.0.3\src\interfaces\libpq\libpq-int.h(481) : error
C2371: 'bool' : redefinition; different basic types
        d:\postgresql-8.0.3\src\include\c.h(174) : see declaration of
'bool'
d:\postgresql-8.0.3\src\interfaces\libpq\libpq-int.h(481) : error
C2143: syntax error : missing ';' before '*'
d:\postgresql-8.0.3\src\interfaces\libpq\libpq-int.h(481) : error
C2059: syntax error : ')'
...

It looks like  sigset_t  is not defined.
Please help.

Pit :-)