Fix the autoconf/makefile.am changes to be consistent.

Create a global SidebarNeedsRedraw to indicate a redraw is needed,
instead of putting sb_draw() everywhere in the code.

Create a menu_redraw_sidebar() function and use the REDRAW_SIDEBAR
flag instead of piggy-backing it inside the index loop.

Fix curs_main.c and pager.c to be a bit cleaner by using the global and
REDRAW_SIDEBAR.

Start to clean up some of the buffy code, but this needs to refactored
and fixed.