Fix/Workaround T46412: Defocus node not working on Windows 32 bit

The issue was caused by some functions in compositor returning
garbage values. Partially the issue was caused by vc12_xp toolset
we're using, but even with regular vc120 toolset nodes like bokeh
image did not work correct.

This is a bit weird solution, which could indicate some sort
of compiler bug, but is also actually makes sense because we do
use SSE intrinsics in the compositor now. Maybe it all gets
interfered in some way.

In any case, if someone wants to find a real solution for the
issue please go ahead.

This shouldn't have affect on supported platform because we
already demand CPU to have SSE2 support.

source/blender/compositor/CMakeLists.txt

@@ -547,6 +547,11 @@ if(WITH_COMPOSITOR_WERROR)
 	ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS C_WERROR -Werror)
 endif()
 
+if(MSVC)
+	set(CMAKE_C_FLAGS "${CMAKE_CXX_FLAGS} /arch:SSE2")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:SSE2")
+endif()
+
 data_to_c(${CMAKE_CURRENT_SOURCE_DIR}/operations/COM_OpenCLKernels.cl
           ${CMAKE_CURRENT_BINARY_DIR}/operations/COM_OpenCLKernels.cl.h SRC)