Better fix for #36935 and 36316:

* 32 bit GCC builds now have the SSE BVH optimizations turned off, but still
  compile with SSE flags for better performance.

* White color when rendering on Windows seems to have been unrelated to SSE,
  rather it was a graphics driver not supporting half float textures, added a
  check for that now.

intern/cycles/util/util_system.cpp

@@ -116,8 +116,7 @@ int system_cpu_bits()
 	return (sizeof(void*)*8);
 }
 
-/* SSE optimization disabled for now on 32 bit, see bug #36316 and #36935 */
-#if defined(__x86_64__) || defined(_M_X64) // ((defined(i386) || defined(_M_IX86))
+#if defined(__x86_64__) || defined(_M_X64) || defined(i386) || defined(_M_IX86)
 
 struct CPUCapabilities {
 	bool x64;