Fix for the Linux build

Bug 19162574

Change-Id: I22a3630104d22c52683f326ad1dd1a0ed334ff93
Reviewed-on: https://swiftshader-review.googlesource.com/1840
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>
diff --git a/src/OpenGL/libGLESv2/Image.cpp b/src/OpenGL/libGLESv2/Image.cpp
index 7ffa209..a78694c 100644
--- a/src/OpenGL/libGLESv2/Image.cpp
+++ b/src/OpenGL/libGLESv2/Image.cpp
@@ -50,7 +50,7 @@
 	template<DataType dataType>
 	void LoadImageRow(const unsigned char *source, unsigned char *dest, GLint xoffset, GLsizei width)
 	{
-		dataType::unimplemented_function;
+		UNIMPLEMENTED();
 	}
 
 	template<>