asn1: Better handling of >63 named bits/ints

First, we enlarge Member's val field to int64_t.

Then we warn about skipping 2int, int2, and parse units glue for such
things with too-large members.

And we error out when generating the template for such things with
>UINT32_MAX members.

What about too-negative members?  That could be a thing for INTEGER /
ENUMERATED.  We'll look at that later.

lib/asn1/gen_encode.c

@@ -226,7 +226,7 @@ encode_type (const char *name, const Type *t, const char *tmpstr)
 	    fprintf (codefile,
 		     "if((%s)->%s) {\n"
 		     "c |= 1<<%d;\n",
-		     name, m->gen_name, 7 - m->val % 8);
+		     name, m->gen_name, (int)(7 - m->val % 8));
 	    fprintf (codefile,
 		     "}\n");
 	}