pgsql: Fix statement_timeout on Win32 so that it properly treats

Log Message:
-----------
Fix statement_timeout on Win32 so that it properly treats micro-seconds
as micro-seconds, rather than as 100 microseconds, as it does now.  This
actually fixes all setitimer calls on Win32, but statement_timeout is
the most visible fix.

Backpatch to 8.1.X.  8.0 works as documented.

Modified Files:
--------------
    pgsql/src/backend/port/win32:
        timer.c (r1.9 -> r1.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32/timer.c.diff?r1=1.9&r2=1.10)