found on fresh git with libFuzzer (on x86_64 Linux)

Feed the attached file to the following target function,
it'll never finish.

The stack trace:

#0  tt_cmap12_next
#1  0x0000000000447a59 in tt_cmap12_char_next
#2  0x000000000040b6b7 in FT_Get_Next_Char
#3  0x0000000000457f18 in af_face_globals_compute_style_coverage
#4  af_face_globals_new
#5  0x0000000000458861 in af_loader_reset
#6  af_loader_load_glyph
#7  af_autofitter_load_glyph
#8  0x000000000040dcda in FT_Load_Glyph
#9  0x0000000000407925 in TestOneInput


void TestOneInput(const unsigned char *data, size_t size) {
  FT_Face face;
  if (size < 1) return;
  FT_Int32 load_flags = FT_LOAD_DEFAULT;
  FT_Render_Mode  render_mode = FT_RENDER_MODE_NORMAL;
  if (!FT_New_Memory_Face(library, data, size, 0, &face)) {
    unsigned first_index = 0;
    for (unsigned i = first_index; i < (unsigned int)face->num_glyphs; i++) {
      if (FT_Load_Glyph(face, i, load_flags)) continue;
      if (FT_Render_Glyph(face->glyph, render_mode)) continue;
    }
    FT_Done_Face(face);
  }
}

This is probably a bug by itself, but also cases like this
completely ruin our ability to fuzz FT_Load_Glyph