Added message statements to print if simd instructions are being enabled.

dlib/cmake

@@ -32,10 +32,13 @@ if (CMAKE_COMPILER_IS_GNUCXX OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang"
     option(USE_AVX_INSTRUCTIONS  "Compile your program with AVX instructions"  OFF)
     if(USE_AVX_INSTRUCTIONS)
         add_definitions(-mavx)
+        message(STATUS "Enabling AVX instructions")
     elseif (USE_SSE4_INSTRUCTIONS)
         add_definitions(-msse4)
+        message(STATUS "Enabling SSE4 instructions")
     elseif(USE_SSE2_INSTRUCTIONS)
         add_definitions(-msse2)
+        message(STATUS "Enabling SSE2 instructions")
     endif()
 elseif (MSVC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC") # else if using Visual Studio 
     # Use SSE2 by default when using Visual Studio.
@@ -52,12 +55,14 @@ elseif (MSVC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC") # else if using Visu
     check_type_size( "void*" SIZE_OF_VOID_PTR)
     if(USE_AVX_INSTRUCTIONS)
         add_definitions(/arch:AVX)
+        message(STATUS "Enabling AVX instructions")
     elseif (USE_SSE4_INSTRUCTIONS)
         # Visual studio doesn't have an /arch:SSE2 flag when building in 64 bit modes.
         # So only give it when we are doing a 32 bit build.
         if (SIZE_OF_VOID_PTR EQUAL 4)
             add_definitions(/arch:SSE2)  
         endif()
+        message(STATUS "Enabling SSE4 instructions")
         add_definitions(-DDLIB_HAVE_SSE2)
         add_definitions(-DDLIB_HAVE_SSE3)
         add_definitions(-DDLIB_HAVE_SSE41)
@@ -67,6 +72,7 @@ elseif (MSVC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC") # else if using Visu
         if (SIZE_OF_VOID_PTR EQUAL 4)
             add_definitions(/arch:SSE2)
         endif()
+        message(STATUS "Enabling SSE2 instructions")
         add_definitions(-DDLIB_HAVE_SSE2)
     endif()
 endif()