Allow one to specify the AWK used in the environment(commandline).

Gawk is blowing up when run natively on the sparc64 -- leading to totally
bogus kernel values (all "0x0").  Good ole BWK awk works fine however.

sys/kern/genassym.sh

@@ -23,7 +23,7 @@ case $# in
 *)	usage;;
 esac
 
-${NM:='nm'} "$1" | awk '
+${NM:='nm'} "$1" | ${AWK:='awk'} '
 / C .*sign$/ {
 	sign = substr($1, length($1) - 3, 4)
 	sub("^0*", "", sign)