Port to OpenBSD 5.1.

Port to OpenBSD 5.1.

* frame.c (Fmouse_position, Fmouse_pixel_position):
* xdisp.c (produce_stretch_glyph):
Declare local vars only when they're needed.
This is clearer and avoids a warning on OpenBSD about unused vars.
* frame.h (FRAME_WINDOW_P): Always evaluate its argument.
This is safer, and avoids OpenBSD warnings about unused vars.
* keyboard.c (record_menu_key): Remove unnecessary decl.
(poll_timer): Define only if POLL_FOR_INPUT is defined.
* unexelf.c (ELFSIZE) [!ElfW]: Do not define if already defined,
as our definition clashes with OpenBSD's.
* xfaces.c (load_face_colors, check_lface_attrs)
(get_lface_attributes_no_remap, get_lface_attributes)
(lface_fully_specified_p, x_supports_face_attributes_p)
(tty_supports_face_attributes_p, face_fontset, realize_face)
(realize_x_face, realize_tty_face):
Declare parameters to be Lisp_Object[LFACE_VECTOR_SIZE], not
merely Lisp_Object *.  This is more informative and avoids
a warning on OpenBSD about accessing beyond an object's size.