clang-14 on OSX, but not clang-14 on x86_64-pc-linux-gnu, fails
class template argument deduction when given:
```
char *c1 = initializer();
const char *c2 = c1 + 1;
std::span{c1, c2};
```
clang correctly refuses to match this to `std::span(pointer, pointer)`,
but fails to find the constructor `std::span(iterator, sentinel)`.
Work around this by changing the type of the sentinel from
`const uint8_t *` to `color_palette_index *` (an alias of `uint8_t *`).
Reported-by: Kreeblah <https://github.com/dxx-rebirth/dxx-rebirth/issues/664>
This started out as underline, but one of the special drawing modes uses
it to draw an underline-width block across the entire vertical height of
the character.
Most callers do not need it, and it is only vaguely related to the
purpose of measuring a particular string. For those callers that need
it, lift it out.
A prior conversion changed the actual rendering to use the argument
cv_font, but still picked which render function to use based on the
flags for the active font. Switch to use only the supplied font.
Commit d355ef4030 removed a seemingly unnecessary modification of the
global variable grd_curcanv->cv_font, after eliminating all local reads
of it. However, a non-local read, buried in listbox_mouse, depended on
grd_curcanv->cv_font being set to a MEDIUM font. After that commit,
grd_curcanv->cv_font retained its prior value, which is not a MEDIUM
font. This caused listbox_mouse to compute an incorrect height of the
lines in the listbox, which manifested as the game choosing the wrong
line when the mouse is clicked in the listbox.
Fix the problem by explicitly using MEDIUM3_FONT, since that was
usually the value left in grd_curcanv->cv_font prior to that commit. In
some cases, a different MEDIUM font would be left there, but all the
MEDIUM fonts have the same height, so they are interchangeable for this
purpose.
Reported-by: Q3BFG10K <https://github.com/dxx-rebirth/dxx-rebirth/issues/498>
Fixes: d355ef4030 ("Pass font to various drawing functions")
Bitmaps based on grs_main_bitmap own their data. Bitmaps based on
grs_bitmap do not. Adjust prototypes to prevent initializing a
grs_main_bitmap with data it will not own.
`build_colormap_good` only took `used` to clear it. Only one caller
needed it cleared. Move the clear into that caller. Remove the
parameter from all calls.
