The commit "Do not compute link language for LOCATION" was wrong.  The
variables

  CMAKE_STATIC_LIBRARY_PREFIX_Java
  CMAKE_STATIC_LIBRARY_SUFFIX_Java

are used for building Java .jar files.  This commit re-enables the
feature and documents the variables:

  CMAKE_EXECUTABLE_SUFFIX_<LANG>
  CMAKE_IMPORT_LIBRARY_PREFIX_<LANG>
  CMAKE_IMPORT_LIBRARY_SUFFIX_<LANG>
  CMAKE_SHARED_LIBRARY_PREFIX_<LANG>
  CMAKE_SHARED_LIBRARY_SUFFIX_<LANG>
  CMAKE_SHARED_MODULE_PREFIX_<LANG>
  CMAKE_SHARED_MODULE_SUFFIX_<LANG>
  CMAKE_STATIC_LIBRARY_PREFIX_<LANG>
  CMAKE_STATIC_LIBRARY_SUFFIX_<LANG>

Instead of making separate, repetitive entries for the _<LANG> variable
documentation, we just mention the per-language name in the text of the
platform-wide variable documentation.  Internally we keep undocumented
definitions of these properties to satisfy CMAKE_STRICT mode.