stb_truetype: Remove dead assignments

Confirmed from the OpenType spec that there's nothing missing
here. (These were just annotations listing the total sizes of
the tables, but this is not used for anything here.)

Fixes issue #704.

stb_truetype.h

@@ -2454,8 +2454,6 @@ static stbtt_int32  stbtt__GetGlyphClass(stbtt_uint8 *classDefTable, int glyph)
 
             if (glyph >= startGlyphID && glyph < startGlyphID + glyphCount)
                 return (stbtt_int32)ttUSHORT(classDef1ValueArray + 2 * (glyph - startGlyphID));
-
-            classDefTable = classDef1ValueArray + 2 * glyphCount;
         } break;
 
         case 2: {
@@ -2478,8 +2476,6 @@ static stbtt_int32  stbtt__GetGlyphClass(stbtt_uint8 *classDefTable, int glyph)
                 else
                     return (stbtt_int32)ttUSHORT(classRangeRecord + 4);
             }
-
-            classDefTable = classRangeRecords + 6 * classRangeCount;
         } break;
 
         default: {