linux: hack around arabic advances in harfbuzz

third_party/harfbuzz/src/harfbuzz-shaper.h

 /*
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This is part of HarfBuzz, an OpenType Layout engine library.
  *
  * Permission is hereby granted, without written agreement and without
  * license or royalty fees, to use, copy, modify, and distribute this
  * software and its documentation for any purpose, provided that the
  * above copyright notice and the following two paragraphs appear in
  * all copies of this software.
@@ skipping 136 matching lines @@
 
 
 typedef enum {
     HB_LeftToRight = 0,
     HB_RightToLeft = 1
 } HB_StringToGlyphsFlags;
 
 typedef enum {
     HB_ShaperFlag_Default = 0,
     HB_ShaperFlag_NoKerning = 1,
-    HB_ShaperFlag_UseDesignMetrics = 2
+    HB_ShaperFlag_UseDesignMetrics = 1 << 1,
+    /* Arabic vowels in some fonts (Times New Roman, at least) have
+       non-zero advances, when they should be zero.  Setting this shaper
+       flag causes us to zero out the advances for mark glyphs. */
+    HB_ShaperFlag_ArabicHack = 1 << 2
 } HB_ShaperFlag;
 
 /* 
    highest value means highest priority for justification. Justification is done by first inserting kashidas
    starting with the highest priority positions, then stretching spaces, afterwards extending inter char
    spacing, and last spacing between arabic words.
    NoJustification is for example set for arabic where no Kashida can be inserted or for diacritics.
 */
 typedef enum {
     HB_NoJustification= 0,   /* Justification can't be applied after this glyph */
@@ skipping 97 matching lines @@
 
     /* internal */
     HB_Bool kerning_applied;                /* output: true if kerning was applied by the shaper */
 };
 
 HB_Bool HB_ShapeItem(HB_ShaperItem *item);
 
 HB_END_HEADER
 
 #endif