player: Drop long-disabled code to resolve IP addresses

Disabled since commit 32fac04 (v4.2.13) because it could at the time
use more stack space than we provided.  Additional issues: code still
uses obsolete gethostbyaddr() rather than getnameinfo(), and we
provide only 512 bytes for host names instead of the customary
NI_MAXHOST (1025) bytes.

All three issues would be easy enough to fix.  What's not so easy is
to avoid blocking on the synchronous DNS lookup.  Without that,
connecting repeatedly from a range of addresses with slow reverse
lookup could conceivably be employed as a denial of service attack.

We've been living without reverse lookup for close to ten years.  Bury
the corpse, and move on.

Bonus: sizeof(struct natstr) is cut in half.

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/misc.h

@@ -29,7 +29,7 @@
  *
  *  Known contributors to this file:
  *     Doug Hay, 1998
- *     Markus Armbruster, 2004-2013
+ *     Markus Armbruster, 2004-2014
  */
 
 #ifndef MISC_H
@@ -51,15 +51,6 @@
 #define ATTRIBUTE(attrs)
 #endif
 
-/*
- * This uses a lot of thread stack with some versions of GNU libc,
- * which can lead to nasty heap smashes (observed with 2.2.93).
- * Disabled for now, until we readjust thread stack sizes.
- */
-#if 0
-#define RESOLVE_IPADDRESS	/* resolve ip addresses into hostnames */
-#endif
-
 #ifndef bit
 #define bit(x)		(1<<(x))
 #endif