libpayload: Fix variable shadowing in PDCurses

PDCurses has a function called overlay() and also uses
overlay as a variable name in some functions.

This patch fixes the ambiguity that caused warnings like
curses/PDCurses-3.4/pdcurses/overlay.c: In function '_copy_win':
curses/PDCurses-3.4/pdcurses/overlay.c:51:39: warning: declaration of 'overlay' shadows a global declaration [-Wshadow]
In file included from curses/PDCurses-3.4/curspriv.h:16:0,
                 from curses/PDCurses-3.4/pdcurses/overlay.c:3:
curses/PDCurses-3.4/curses.h:1014:9: warning: shadowed declaration is here [-Wshadow]

Change-Id: I907653df0c8bb32c98bdcbc6476e94d2da6e0e90
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/2906
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
1 file changed