Moved __mingw_get_msvcrt_handle to libmsvcrt.a and hardcode it to load msvcrt.dll (other msvcr*.dll variants no longer use that function).

git-svn-id: svn+ssh://svn.code.sf.net/p/mingw-w64/code/trunk@5898 4407c894-4637-0410-b4f5-ada5f102cad1