Fix deSign's NaN check

deSign() is using deIsNaN() to check for NaN which can cause
exceptions. deIsNaN() in replaced with deDoubleIsIEEENaN()
in deSign to avoid triggering exceptions.

VK-GL-CTS issue: 5182
Components: Framework

Change-Id: I98d76177afa01f195ee386e074dc506e574ca845

Author: madeeha

framework/delibs/debase/deMath.h

@@ -251,7 +251,7 @@ float deFloatFractExp(float x, int *exponent);
 
 DE_INLINE double deSign(double x)
 {
-    return deIsNaN(x) ? x : (double)((x > 0.0) - (x < 0.0));
+    return deDoubleIsIEEENaN(x) ? x : (double)((x > 0.0) - (x < 0.0));
 }
 DE_INLINE int deIntSign(double x)
 {