ENH: Pass dependent library search path to linker on some platforms.

  - Move runtime path ordering out of cmComputeLinkInformation
    into its own class cmOrderRuntimeDirectories.
  - Create an instance of cmOrderRuntimeDirectories for runtime
    path ordering and another instance for dependent library
    path ordering.
  - Replace CMAKE_DEPENDENT_SHARED_LIBRARY_MODE with explicit
    CMAKE_LINK_DEPENDENT_LIBRARY_FILES boolean.
  - Create CMAKE_LINK_DEPENDENT_LIBRARY_DIRS boolean.
  - Create variables to specify -rpath-link flags:
      CMAKE_SHARED_LIBRARY_RPATH_LINK_<LANG>_FLAG
      CMAKE_EXECUTABLE_RPATH_LINK_<LANG>_FLAG
  - Enable -rpath-link flag on Linux and QNX.
  - Documentation and error message updates