Fix warnings and 64-bit issues in pthread testcases. See pthread-win32 commit 1183e5ac etc.
* winsup.api/pthread/rwlock2.c: Ditto. * winsup.api/pthread/rwlock3.c: Ditto. * winsup.api/pthread/rwlock4.c: Ditto. * winsup.api/pthread/rwlock5.c: Ditto. * winsup.api/pthread/rwlock6.c: Ditto.
* winsup.api/pthread/rwlock2.c: Ditto. * winsup.api/pthread/rwlock3.c: Ditto. * winsup.api/pthread/rwlock4.c: Ditto. * winsup.api/pthread/rwlock5.c: Ditto. * winsup.api/pthread/rwlock6.c: Ditto. * winsup.api/pthread/rwlock7.c: Ditto.