lib/, src/: Use %F instead of %Y-%m-%d with strftime(3)

%F is specified by ISO C99.  It adds semantic meaning as printing an
ISO 8601 date.

Scripted change:

	$ cat ~/tmp/spatch/strftime_F.sp
	@@
	@@

	- "%Y-%m-%d"
	+ "%F"
	$ find contrib/ lib* src/ -type f \
	| xargs spatch --sp-file ~/tmp/spatch/strftime_F.sp --in-place

Signed-off-by: Alejandro Colomar <alx@kernel.org>

src/chage.c

@@ -247,7 +247,7 @@ print_day_as_date(long day)
 		return;
 	}
 
-	STRFTIME(buf, iflg ? "%Y-%m-%d" : "%b %d, %Y", &tm);
+	STRFTIME(buf, iflg ? "%F" : "%b %d, %Y", &tm);
 	(void) puts (buf);
 }