This corrects ipv6.h to recognise global addresses as starting
with the byte 0x20 instead of 0x02.  I've tested it; it works.

Reference: /n/sources/patch/applied/ipv6-through-gw
Date: Wed Jun 16 19:17:30 CES 2004

--- /sys/src/9/ip/ipv6.h	Wed Jun 16 19:17:30 2004
+++ /sys/src/9/ip/ipv6.h	Wed Jun 16 19:17:30 2004
@@ -2,7 +2,7 @@
 #define isv6mcast(addr) ((addr)[0] == 0xff)
 #define islinklocal(addr) ( ((addr)[0] == 0xfe) && ((addr)[1] == 0x80) )
 #define issitelocal(addr) ( ((addr)[0] == 0xfe) && ((addr)[1] == 0xc0) )
-#define isv6global(addr) ( (addr)[0] == 0x2 )
+#define isv6global(addr) ( (addr)[0] == 0x20 )
 #define optexsts(np) (nhgets((np)->ploadlen) > 24)
 #define issmcast(addr) (memcmp((addr), v6solicitednode, 13) == 0)