Make Reactor destination variables non-const.

Bug swiftshader:27

Change-Id: I53e2e4858b10d810f649907fda98dc7863752551
Reviewed-on: https://swiftshader-review.googlesource.com/8090
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-on: https://swiftshader-review.googlesource.com/8232
Reviewed-by: Alexis Hétu <sugoi@google.com>
diff --git a/src/Shader/PixelRoutine.cpp b/src/Shader/PixelRoutine.cpp
index 2025da7..7e6c943 100644
--- a/src/Shader/PixelRoutine.cpp
+++ b/src/Shader/PixelRoutine.cpp
@@ -868,7 +868,7 @@
 		}
 	}
 
-	void PixelRoutine::blendFactor(const Vector4s &blendFactor, const Vector4s &current, const Vector4s &pixel, BlendFactor blendFactorActive)
+	void PixelRoutine::blendFactor(Vector4s &blendFactor, const Vector4s &current, const Vector4s &pixel, BlendFactor blendFactorActive)
 	{
 		switch(blendFactorActive)
 		{
@@ -949,7 +949,7 @@
 		}
 	}
 
-	void PixelRoutine::blendFactorAlpha(const Vector4s &blendFactor, const Vector4s &current, const Vector4s &pixel, BlendFactor blendFactorAlphaActive)
+	void PixelRoutine::blendFactorAlpha(Vector4s &blendFactor, const Vector4s &current, const Vector4s &pixel, BlendFactor blendFactorAlphaActive)
 	{
 		switch(blendFactorAlphaActive)
 		{
@@ -1899,7 +1899,7 @@
 		}
 	}
 
-	void PixelRoutine::blendFactor(const Vector4f &blendFactor, const Vector4f &oC, const Vector4f &pixel, BlendFactor blendFactorActive)
+	void PixelRoutine::blendFactor(Vector4f &blendFactor, const Vector4f &oC, const Vector4f &pixel, BlendFactor blendFactorActive)
 	{
 		switch(blendFactorActive)
 		{
@@ -1970,7 +1970,7 @@
 		}
 	}
 
-	void PixelRoutine::blendFactorAlpha(const Vector4f &blendFactor, const Vector4f &oC, const Vector4f &pixel, BlendFactor blendFactorAlphaActive)
+	void PixelRoutine::blendFactorAlpha(Vector4f &blendFactor, const Vector4f &oC, const Vector4f &pixel, BlendFactor blendFactorAlphaActive)
 	{
 		switch(blendFactorAlphaActive)
 		{