Cycles: Fix building of OpenCL kernels after volume optimization commit

OpenCL is C based, so no support for operators.

Related commit: 7377d411b4

intern/cycles/util/util_math_int3.h

@@ -76,8 +76,6 @@ ccl_device_inline int3 clamp(const int3& a, int3& mn, int mx)
 	                 clamp(a.z, mn.z, mx));
 #endif
 }
-#endif  /* !__KERNEL_OPENCL__ */
-
 
 ccl_device_inline bool operator==(const int3 &a, const int3 &b)
 {
@@ -93,6 +91,7 @@ ccl_device_inline bool operator<(const int3 &a, const int3 &b)
 {
 	return a.x < b.x && a.y < b.y && a.z < b.z;
 }
+#endif  /* !__KERNEL_OPENCL__ */
 
 CCL_NAMESPACE_END