Fix unaligned access faults on alpha.

This one is strange and goes against my rusty compiler knowledge.

The global declaration

struct sockaddr whereto;

produces for both i386 && alpha:

        .comm   whereto,16,1

which means common storage, byte aligned. Ahem. I though structs
were supposed to be ALDOUBLE always? I mean, w/o pragma packed?

Later on, this address is coerced to:

		to = (struct sockaddr_in *)&whereto;

Up until now, we've been fine on alpha because the address
just ended up aligned to a 4 byte boundary. Lately, though,
it end up as:

0000000120027b0f B whereto

And, tra la, you get unaligned access faults. The solution I picked, in
lieu of understanding what the compiler was doing, is to put whereto
as a union of a sockaddr and sockaddr_in. That's more formally correct
if somewhat awkward looking.

sbin/ping/ping.c

@@ -146,7 +146,15 @@ int options;
 int mx_dup_ck = MAX_DUP_CHK;
 char rcvd_tbl[MAX_DUP_CHK / 8];
 
-struct sockaddr whereto;	/* who to ping */
+/*
+ * Use a union to coerce alignment to at least sockaddr_in's alignment.
+ * This avoids unaligned access faults on alpha.
+ */
+union {
+	struct sockaddr 	_w2;	/* who to ping */
+	struct sockaddr_in 	_w2_in;	/* who to ping */
+} ww;
+#define	whereto	ww._w2
 int datalen = DEFDATALEN;
 int s;				/* socket file descriptor */
 u_char outpack[MAXPACKET];