Revision 1504501

In the Windows project generator: Make libintl a proper optional dependency,
instead of specializing the includes/libpath/library everywhere.

* build.conf
  (libsvn_subr): Use libintl.
  (intl): New marker project

* build/generator/gen_win.py
  (get_win_includes): Just add includes. Remove libintl support.
    Remove duplicated items.
  (get_win_lib_dirs): Simplify addition. Remove duplicated items.
  (get_win_libs): Remove specialized handling of libintl.

* build/generator/gen_win_dependencies.py
  (SVNCommonLibrary): Add extra_include_dir option.
  (find_libraries): Call _find_libintl.
  (_find_apr): Really handle an install location.
  (_find_openssl): Properly set bin_dir
  (_find_libintl): New function.

* gen-make.py
  (Options.add): Make overwriting old values optional.
  (.): Don't override every --apr-* argument via --with-httpd.

* win-tests.py
  (locate_libs): Remove libintl specific copying.