Merge performance fix for cmsDupToneCurve from previous upstream branch.

core/src/fxcodec/lcms2/lcms2-2.6/src/cmsgamma.c

 //---------------------------------------------------------------------------------
 //
 //  Little Color Management System
 //  Copyright (c) 1998-2013 Marti Maria Saguer
 //
 // Permission is hereby granted, free of charge, to any person obtaining
 // a copy of this software and associated documentation files (the "Software"),
 // to deal in the Software without restriction, including without limitation
 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
 // and/or sell copies of the Software, and to permit persons to whom the Software
@@ skipping 804 matching lines @@
     Curve[0] = Curve[1] = Curve[2] = NULL;
 }
 
 
 // Duplicate a gamma table
 cmsToneCurve* CMSEXPORT cmsDupToneCurve(const cmsToneCurve* In)
 {   
         // Xiaochuan Liu
         // fix openpdf bug(mantis id:0055683, google id:360198)
         // the function CurveSetElemTypeFree in cmslut.c also needs to check pointer
-    if (In == NULL || In ->InterpParams == NULL) return NULL;
+    if (In == NULL || In ->InterpParams == NULL || In ->Segments == NULL || In ->Table16 == NULL) return NULL;

[jun_fang, 2014/09/03 18:52:13]

Seems that these the checking for |In ->Segments == NULL || In -
      >Table16 == NULL| was removed when lcms was upgraded from 2.0 to 2.6. I am
double checking with the author to know its reason.  

 
     return  AllocateToneCurveStruct(In ->InterpParams ->ContextID, In ->nEntries, In ->nSegments, In ->Segments, In ->Table16);
 }
 
 // Joins two curves for X and Y. Curves should be monotonic.
 // We want to get
 //
 //      y = Y^-1(X(t))
 //
 cmsToneCurve* CMSEXPORT cmsJoinToneCurve(cmsContext ContextID,
@@ skipping 453 matching lines @@
     }
 
     // Take a look on SD to see if gamma isn't exponential at all
     Std = sqrt((n * sum2 - sum * sum) / (n*(n-1)));
 
     if (Std > Precision)
         return -1.0;
 
     return (sum / n);   // The mean
 }