Support native image resizing on MS-Windows

* src/w32term.c (x_draw_image_foreground): Scale the image if
the requested dimensions are different from the bitmap
dimensions.
* src/image.c (Fimage_scaling_p): Return t when HAVE_NTGUI.
(x_set_image_size) [HAVE_NTGUI]: Record the scaled dimensions
in the image struct.
* src/dispextern.h (HAVE_NATIVE_SCALING): Define when
HAVE_NTGUI as well.

* etc/NEWS: Update the announcement of native image scaling.
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Status Job ID Name Coverage
  Test
passed #602
test-all

00:47:55