pgsql: Create wrapper pgwin32_safestat() and redefine stat() to it on

Log Message:
-----------
Create wrapper pgwin32_safestat() and redefine stat() to it
on win32, because the stat() function in the runtime cannot
be trusted to always update the st_size field.

Per report and research by Sergey Zubkovsky.

Tags:
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REL8_3_STABLE

Modified Files:
--------------
    pgsql/src/include:
        port.h (r1.116.2.1 -> r1.116.2.2)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/port.h?r1=1.116.2.1&r2=1.116.2.2)
    pgsql/src/port:
        dirmod.c (r1.51 -> r1.51.2.1)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/port/dirmod.c?r1=1.51&r2=1.51.2.1)