rename netbsd.500 to bsd.500

In past releases of NetHack, there was a myriad of different hints
files for different operating systems, and even different versions
of operating systems.

It made maintenance a chore, because all the variable hints files
had to be updated for a wanted change, or (as typically was the
case), some lesser-used hints files were left behind and became
outdated.

Instead of going down that road again, this renames
    sys/unix/hints/netbsd.500
to
    sys/unix/hints/bsd.500

Where things need to differ for a different bsd flavour,
the differences can be shrouded in things like

    .if ${WHICHBSD} == "NETBSD"
    .else
    .endif

This change is being done to make maintenance easier, at the
cost of making the resulting Makefiles a little more complex,
but there won't be as many separate Makefile hints to maintain.

This commit is being done instead of merging pull request #1531
which would add a new sys/unix/hints/openbsd.500 file.

Only tested on NetBSD so far. Please let us know if there's
an issue on other bsd's, and we will attempt to fix thos issues.

Closes #1531

Close

include/unixconf.h

@@ -338,7 +338,7 @@
 #endif
 
 #if defined(BSD) || defined(ULTRIX)
-#if !defined(DGUX) && !defined(SUNOS4) && !defined(__NetBSD__)
+#if !defined(DGUX) && !defined(SUNOS4) && !defined(__NetBSD__) && !defined(__FreeBSD__)
 #define memcpy(d, s, n) bcopy(s, d, n)
 #define memcmp(s1, s2, n) bcmp(s2, s1, n)
 #endif