pgsql: Move pthread-win32.h to /port, modify bcc/msvc makefiles.

Log Message:
-----------
Move pthread-win32.h to /port, modify bcc/msvc makefiles.

Modified Files:
--------------
    pgsql/src/interfaces/libpq:
        bcc32.mak (r1.22 -> r1.23)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/bcc32.mak.diff?r1=1.22&r2=1.23)
        win32.mak (r1.37 -> r1.38)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/win32.mak.diff?r1=1.37&r2=1.38)

Added Files:
-----------
    pgsql/src/port:
        pthread-win32.h (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/port/pthread-win32.h?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/src/interfaces/libpq:
        pthread-win32.h
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/pthread-win32.h)