Avoid direct writes to contents member of struct Lisp_Vector.

Avoid direct writes to contents member of struct Lisp_Vector.
* lisp.h (vcopy): New function to copy data into vector.
* dispnew.c (Fframe_or_buffer_changed_p): Use AREF and ASET.
* fns.c (Ffillarray): Use ASET.
* keyboard.c (timer_check_2): Use AREF and ASET.
(append_tool_bar_item, Frecent_keys): Use vcopy.
* lread.c (read_vector): Use ASET.
* msdos.c (Frecent_doskeys): Use vcopy.
* xface.c (Finternal_copy_lisp_face): Use vcopy.
(Finternal_merge_in_global_face): Use ASET and vcopy.
* xfont.c (xfont_list_pattern): Likewise.