test/CMakeLists.txt: Append /MANIFEST:NO with space instead of list-append

Author: emmenlau

test/CMakeLists.txt

@@ -111,7 +111,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     endif()
   else() # We are using clang-cl
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_cxx_std_flag} /bigobj")
-    set(CMAKE_EXE_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS} /MANIFEST:NO)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} /MANIFEST:NO")
     add_definitions(-D_CRT_SECURE_NO_WARNINGS)
     add_definitions(-D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING)
     if (XTENSOR_DISABLE_EXCEPTIONS)