scratch/allow-custom-null-and-false-objects-in-jsonc

Problem reported by Eli Zaretskii in:
https://lists.gnu.org/r/emacs-devel/2018-06/msg00238.html
* src/lisp.h (struct Lisp_Symbol, union vectorlike_header)
(struct Lisp_Cons, struct Lisp_String):
Do not check alignment if !USE_LSB_TAG, as alignment is
needed only if we are tagging the low-order bits.

* src/xfaces.c (face-remapping-alist): remove an empty ‘(3)’ introduced
in a docstring by mistake.

Extend face specifications to support the notion of filtering to a
specific context and add a filter that limits a face specification to
windows having a certain parameter.

* src/xfaces.c:
(evaluate_face_filter,filter_face_ref): New functions.
(merge_face_ref): Ignore filtered face specifications.
(Fx_list_fonts,get_lface_attributes,merge_face_vectors)
(merge_named_face,merge_face_ref,merge_face_ref)
(Finternal_merge_in_global_face,Fface_font,lookup_named_face)
(lookup_basic_face,Fface_attributes_as_vector)
(x_supports_face_attributes_p)
(Fdisplay_supports_face_attributes_p,realize_named_face)
(compute_char_face,face_at_buffer_position)
(face_at_buffer_position,face_at_buffer_position)
(face_at_buffer_position)
(face_for_overlay_string,face_at_string_position,merge_faces):
Pass window to face machinery.
(syms_of_xfaces): Add :window and :filtered

* src/xdisp.c (init_iterator, handle_face_prop)
(handle_single_display_spec, merge_escape_glyph_face)
(merge_glyphless_glyph_face, get_next_display_element)
(next_element_from_display_vector, append_space_for_newline)
(extend_face_to_end_of_line,highlight_trailing_whitespace)
(maybe_produce_line_number)
(display_line, calc_line_height_property): Pass window to
face machinery.

* src/term.c (tty_menu_activate): Adjust to new face core
function signature.

* src/msdos.c (XMenuActivate): Adjust to new face core
function signature.

* src/fringe.c (draw_fringe_bitmap_1, Fset_fringe_bitmap_face):
Pass window to face machinery.

* src/font.c (font_range, Finternal_char_font): Pass window to
face machinery.

* src/dispnew.c (spec_glyph_lookup_face): Pass window to
face machinery.

* src/dispextern.h:
(lookup_named_face,lookup_basic_face)
(lookup_derived_face,merge_faces):
Add struct window arguments to prototypes.

* src/xwidget.c (kill_buffer_xwidgets): Reindent and use C99
style to fit in 80 columns.

* src/editfns.c (save_excursion_restore): Use clearer names
for locals.  Free earlier, removing the need for a label and goto.

This simplifies callers a bit, and will simplify future changes.
* src/eval.c (record_unwind_protect_excursion): New function.
* src/buffer.c (Fkill_buffer):
* src/bytecode.c (exec_byte_code):
* src/editfns.c (Fsave_excursion, Freplace_buffer_contents):
* src/lread.c (readevalloop, Feval_buffer):
* src/window.c (scroll_command):
Use it.

* src/ftfont.c (ftfont_open2): Don’t increment counter if failing.
Avoid use-after-free once the increment bug is fixed.