merge: upstream fixes (mutt/default)

 * Add ifdefs around new mutt_resize_screen calls.
 * Add multiline and sigwinch handling to mutt_multi_choice. (see #3877)
 * Set pager's REDRAW_SIGWINCH when reflowing windows.
 * Add multiline and sigwinch handling to mutt_yesorno. (closes #3877)
 * Change the sort prompt to use (s)ort style prompts.
 * Handle the pager sort prompt inside the pager.