lisp/term/w32-win.el contained definitions of variables which
were not used on Cygw32.  It is now to split into two files,
common part and Windows native build specific part. The latter
is a new file, lisp/term/w32-nt.el.
* src/image.c (Qlibpng_version, Qlibgif_version)
(Qlibjpeg_version): Don't define on Cygw32 build.
* src/treesit.c (Qtree_sitter__library_abi): Ditto.

* lisp/term/w32-win.el (dynamic-library-alist, libpng-version)
(libgif-version, libjpeg-version, libgnutls-version)
(tree-sitter--library-abi, gui-backend-set-selection)
(gui-backend-get-selection, gui-backend-selection-owner-p)
(gui-selection-exists-p): Moved to lisp/term/w32-nt.el.
* lisp/term/w32-nt.el: New file, separated Windows native build
specific part from lisp/term/w32-win.el.
* lisp/loadup.el: Load term/w32-nt.el on Windows native build.
(Bug#75926)

* src/image.c (svg_load_image): Prefer make_formatted_string to
snprintf, as this simplifies the code and does not truncate the
resulting string arbitrarily.

* src/image.c (make_color_name): New function.
(image_background, image_build_heuristic_mask, png_load_body): Use it.

From a suggestion by Pip Cet.
* src/alloc.c (make_formatted_string): Omit first argument,
to simplify the calling convention.  All callers changed.
* src/doprnt.c (doprnt): Also support %u.  Update doc.

* src/image.c (image_create_x_image_and_pixmap_1): Avoid temporary
variable by passing the value directly to image_error.
(tiff_handler): Prefer image_error to add_to_log for local
consistency.

* src/image.c (image_build_heuristic_mask, png_load_body):
Abort if snprintf truncated.  (If truncation is not possible
here we should use sprintf instead, as that simplifies
automatic runtime checking.)

* src/image.c (image_background, image_build_heuristic_mask)
(png_load_body): Prefer snprintf to sprintf.

* src/image.c (svg_css_length_to_pixels): Restructure so GCC warns
about new enum members.  Add case for RSVG_UNIT_CH.  Warn about
unknown units discovered at runtime.