On FreeBSD/arm, any value > 50 bits will result in a rediculously huge

number being returned for mktime and timegm calls.  Choose 48 because
that works well.  This does reduce the dynamic range of tm_year from
about 2 billion years down to "only" about 9 million years.  Please
contact me if this restriction poses a problem.

Due to the complexity of the code, I admit that I didn't trace down
what, exactly, was overflowing with longer bits.  This fixes software
that we run on the embedded systems we have.

lib/libc/stdtime/localtime.c

@@ -1518,8 +1518,8 @@ const int		do_norm_secs;
 	** If we have more than this, we will overflow tm_year for tmcomp().
 	** We should really return an error if we cannot represent it.
 	*/
-	if (bits > 56)
-		bits = 56;
+	if (bits > 48)
+		bits = 48;
 	/*
 	** If time_t is signed, then 0 is just above the median,
 	** assuming two's complement arithmetic.