Add ListFonts, SetFontPath, and GetFontPath protocol builders to
proto/x11.py and a regression test that reproduces the
doListFontsAndAliases stack buffer overflow.
The test creates a temporary font directory with a fonts.alias file
containing an alias whose target name is 400 bytes -- exceeding the
old XLFDMAXFONTNAMELEN of 256 but under libXfont2's MAXFONTNAMELEN of
1024. It prepends this directory to the font path via SetFontPath, then
sends ListFonts matching the alias name. Without the fix, the server
would copy the oversized resolved name into a 256-byte stack buffer,
causing a stack buffer overflow.
ZDI-CAN-30136
Assisted-by: Claude:claude-opus-4-6
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2228>
