Fixed visual studio errors about openmp compiler flags not being right.

dlib/CMakeLists.txt

@@ -662,7 +662,9 @@ if (NOT TARGET dlib)
       if (OPENMP_FOUND)
          # Enable OpenMP
          target_compile_options(dlib PUBLIC ${OpenMP_CXX_FLAGS}) 
-         target_link_libraries(dlib PUBLIC ${OpenMP_CXX_FLAGS}) 
+         if (NOT MSVC)
+            target_link_libraries(dlib PUBLIC ${OpenMP_CXX_FLAGS}) 
+         endif()
       endif()
       if (UNIX AND NOT DLIB_IN_PROJECT_BUILD)
          if (DLIB_USE_CUDA)
@@ -681,7 +683,9 @@ if (NOT TARGET dlib)
          if (OPENMP_FOUND)
             # Enable OpenMP
             target_compile_options(dlib_shared PUBLIC ${OpenMP_CXX_FLAGS}) 
-            target_link_libraries(dlib_shared PUBLIC ${OpenMP_CXX_FLAGS}) 
+            if (NOT MSVC)
+               target_link_libraries(dlib_shared PUBLIC ${OpenMP_CXX_FLAGS}) 
+            endif()
          endif()
       endif()