Fixed old visual studio check

dlib/cmake_utils/use_cpp_11.cmake

@@ -50,14 +50,14 @@ if (CMAKE_VERSION VERSION_LESS "3.1.2")
          message(FATAL_ERROR "*** Your compiler failed to build a C++11 project, so dlib won't use C++11 features.***")
       endif()
    endif()
+elseif(MSVC AND MSVC_VERSION VERSION_LESS 1900)
+   message(FATAL_ERROR "C++11 is required to use dlib, but the version of Visual Studio you are using is too old and doesn't support C++11.")
 elseif(MSVC AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0.24215.1 ) 
    message(STATUS "NOTE: Visual Studio didn't have good enough C++11 support until Visual Studio 2015 update 3 (v19.0.24215.1)")
    message(STATUS "So we aren't enabling things that require full C++11 support (e.g. the deep learning tools).")
    message(STATUS "Also, be aware that Visual Studio's version naming is confusing, in particular, there are multiple versions of 'update 3'")
    message(STATUS "So if you are getting this message you need to update to the newer version of Visual Studio to use full C++11.")
    set(USING_OLD_VISUAL_STUDIO_COMPILER 1)
-elseif(MSVC AND MSVC_VERSION VERSION_LESS 1900)
-   message(FATAL_ERROR "C++11 is required to use dlib, but the version of Visual Studio you are using is too old and doesn't support C++11.")
 else()  
 
    # Set a flag if the compiler you are using is capable of providing C++11 features.