Add notes to the asctime() and ctime() descriptions to make it

explicit that locale information is not used.  There wasn't anything
that implied it was, but this has confused users.

Doc/lib/libtime.tex

@@ -124,6 +124,7 @@ Convert a tuple representing a time as returned by \function{gmtime()}
 or \function{localtime()} to a 24-character string of the following form:
 \code{'Sun Jun 20 23:21:05 1993'}.  If \var{tuple} is not provided, the
 current time as returned by \function{localtime()} is used.
+Locale information is not used by \function{asctime()}.
 \note{Unlike the C function of the same name, there is no trailing
 newline.}
 \versionchanged[Allowed \var{tuple} to be omitted]{2.1}
@@ -149,6 +150,7 @@ Convert a time expressed in seconds since the epoch to a string
 representing local time. If \var{secs} is not provided, the current time
 as returned by \function{time()} is used.  \code{ctime(\var{secs})}
 is equivalent to \code{asctime(localtime(\var{secs}))}.
+Locale information is not used by \function{ctime()}.
 \versionchanged[Allowed \var{secs} to be omitted]{2.1}
 \end{funcdesc}