Pull up following revision(s) (requested by riastradh in ticket #648):

lib/libc/time/strptime.c: revision 1.66

strptime(3): Declare digit d as time_t.

This doesn't make a semantic difference -- d can only take on the ten
values {0,1,2,3,4,5,6,7,8,9}, and the arithmetic with it later all
comes out the same whether the type is unsigned or time_t, even if
time_t were int32_t instead of int64_t.

But it pacifies overzealous compilers used by downstream users of
this code.  And while it's silly to use a much wider type (64-bit
signed) than is needed here to store a single digit, it doesn't
really hurt either (32-bit unsigned is much larger than needed too).

PR lib/58041

(martin)