Cycles: Fix Architecture logging on x64.

x64 builds with WITH_CYCLES_OPTIMIZED_KERNEL_SSE2 not defined
since SSE2 is the lower bar for x64 cpus. Turning the architecture
logging related if into the last if in the architecture detection
chain, which will never execute unless you turn off all kernels
in de debug flags.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D5579

intern/cycles/device/device_cpu.cpp

@@ -114,6 +114,12 @@ template<typename F> class KernelFunctions {
       architecture_name = "SSE2";
       kernel = kernel_sse2;
     }
+#else
+    {
+      /* Dummy to prevent the architecture if below become
+       * conditional when WITH_CYCLES_OPTIMIZED_KERNEL_SSE2
+       * is not defined. */
+    }
 #endif
 
     if (strcmp(architecture_name, logged_architecture) != 0) {