pgsql: Move copydir.c from src/port to src/backend/storage/file The

Log Message:
-----------
Move copydir.c from src/port to src/backend/storage/file

The previous commit to make copydir() interruptible prevented
postgres.exe from linking on MinGW and Cygwin, because on those
platforms libpgport_srv.a can't freely reference symbols defined
by the backend. Since that code is already backend-specific anyway,
just move the whole file into the backend rather than adding further
kludges to deal with the symbols needed by CHECK_FOR_INTERRUPTS().

This probably needs some further cleanup, but this commit just moves
the file as-is, which should hopefully be enough to turn the
buildfarm green again.

Tags:
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REL8_4_STABLE

Modified Files:
--------------
pgsql/src/backend/storage/file:
Makefile (r1.13 -> r1.13.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/file/Makefile?r1=1.13&r2=1.13.2.1)
pgsql/src/port:
Makefile (r1.37 -> r1.37.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/port/Makefile?r1=1.37&r2=1.37.2.1)

Added Files:
-----------
pgsql/src/backend/storage/file:
copydir.c (r1.1.2.1)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/file/copydir.c?rev=1.1.2.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
pgsql/src/port:
copydir.c
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/port/copydir.c)