[CMAKE] SBSMS: fix compilation error. (#467)

If you try to build local SBSMS with CMake for i686, you get many error messages like this one:

audacity/lib-src/sbsms/src/fft.h:346:29: warning: SSE vector return without SSE enabled changes the ABI [-Wpsabi]

The solution is to add the option provided by SSE_FLAGS.
So, I replicated in this PR the same fix made for local soundtouch and LAME library.

cmake-proxies/sbsms/CMakeLists.txt

@@ -28,6 +28,8 @@ list( APPEND INCLUDES
 list( APPEND OPTIONS
    PRIVATE
       $<$<C_COMPILER_ID:AppleClang,Clang,GNU>:-Wno-enum-compare>
+      ${MMX_FLAG}
+      ${SSE_FLAG}
 )
 
 find_package( Threads )