memory leak in font handling

[uli42]

similar to #586

==380556== 96 bytes in 1 blocks are definitely lost in loss record 294 of 402
==380556==    at 0x483AB65: calloc (vg_replace_malloc.c:760)
==380556==    by 0x4D16C51: FreeTypeLoadXFont (ftfuncs.c:3147)
==380556==    by 0x4D1B05A: FreeTypeGetInfoScalable (ftfuncs.c:3878)
==380556==    by 0x4D105BC: FontFileListOneFontWithInfo.constprop.0 (fontfile.c:1015)
==380556==    by 0x4D10665: FontFileListNextFontWithInfo (fontfile.c:1060)
==380556==    by 0x162FB3: doListFontsWithInfo (NXdixfonts.c:842)
==380556==    by 0x165F86: StartListFontsWithInfo (dixfonts.c:1254)
==380556==    by 0x16F485: ProcListFontsWithInfo (NXdispatch.c:924)
==380556==    by 0x16E674: Dispatch (NXdispatch.c:486)
==380556==    by 0x14E380: main (main.c:350)

The problem here is a bug in libXfont, see https://gitlab.freedesktop.org/xorg/lib/libxfont/-/issues/10

I don't see how we could get around that without circumventing libXfont.