* Makefile (AWK): Default to 'awk'; this is more portable these days.

Suggested by Mike Frysinger in
<http://mm.icann.org/pipermail/tz/2012-October/018397.html>.

Makefile

@@ -231,7 +231,7 @@ zic=		./zic
 ZIC=		$(zic) $(ZFLAGS)
 
 # The name of a Posix-compliant `awk' on your system.
-AWK=		nawk
+AWK=		awk
 
 # The path where SGML DTDs are kept.
 # The default is appropriate for Ubuntu.