Win32 patch to allow compilation

I have applied the following patch to allow Win32 compilation under
MinGW. The patch includes the following changes:

Win32 port is now called 'win32' rather than 'win'
add -lwsock32 on Win32
make gethostname() be only used when kerberos4 is enabled
use /port/getopt.c
new /port/opendir.c routines
disable GUC unix_socket_group on Win32
convert some keywords.c symbols to KEYWORD_P to prevent conflict
create new FCNTL_NONBLOCK macro to turn off socket blocking
create new /include/port.h file that has /port prototypes, move
out of c.h
new /include/port/win32_include dir to hold missing include files
work around ERROR being defined in Win32 includes

As I said on hackers, these changes are minor.

This patch passes all compile/regression tests under Unix.

--
Bruce Momjian | http://candle.pha.pa.us
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