Fix crash with bidi display on the last empty line (bug#6030).

 xdisp.c (display_line): Don't assume 2nd call to
 get_next_display_element cannot return zero.  (Bug#6030)

Move code that bidi-iterates out of display property to a separate function.

 xdisp.c (iterate_out_of_display_property): New function, body from pop_it.
 (pop_it): Use it.

diff --cc src/ChangeLog
index 2119d64,58fdad2..e7ed7c3
--- 1/src/ChangeLog
--- 2/src/ChangeLog
+++ b/src/ChangeLog
@@@ -1,10 -1,10 +1,17 @@@
 -      * xdisp.c (display_line): Fix crash with bidi display on the last
 -      empty line.  (Bug#6030)
+ 2010-04-25  Eli Zaretskii  <eliz@gnu.org>
+ 
++      * xdisp.c (display_line): Don't assume 2nd call to
++      get_next_display_element cannot return zero.  (Bug#6030)
+       (iterate_out_of_display_property): New function, body from pop_it.
+       (pop_it): Use it.
+ 
 +2010-04-24  Glenn Morris  <rgm@gnu.org>
 +
 +      * m/amdx86-64.h (START_FILES, LIB_STANDARD) [__OpenBSD__]:
 +      For clarity, revert to using fixed /usr/lib rather than $CRT_DIR.
 +      (START_FILES, LIB_STANDARD) [__FreeBSD__]: Merge into the generic case,
 +      since CRT_DIR defaults to /usr/lib.  Suggested by Dan Nicolaescu.
 +
  2010-04-24  Eli Zaretskii  <eliz@gnu.org>
  
        * xdisp.c (display_line): Use `reseat' instead of `reseat_1', and