Remove need for elevated command line in Windows

Changes use of mklink in Windows test builds, to create junctions instead of
directory symbolic links. This removes the need for an elevated command prompt
when running cmake to create the Visual Studio project files.

tests/CMakeLists.txt

@@ -115,7 +115,7 @@ if (NOT ${CMAKE_CURRENT_BINARY_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
         if (CMAKE_HOST_UNIX)
             set(command ln -s ${target} ${link})
         else()
-            set(command cmd.exe /c mklink /d ${link} ${target})
+            set(command cmd.exe /c mklink /j ${link} ${target})
         endif()
 
         execute_process(COMMAND ${command}