Issue #4828, Hide experimental commands and options by default.
* subversion/libsvn_subr/opt.c (print_command_info3, print_generic_help_body3): Show commands and options starting with 'x-' only if new 'with_experimental' option is true. (print_generic_help): Extracted from 'svn_opt_print_generic_help3', to take the new 'with_experimental' option. (subcommand_help): Extracted from 'svn_opt_subcommand_help4', to take the new 'with_experimental' option. (svn_opt_print_help5): Let the 'verbose' option control 'with experimental', when printing help. The 'verbose' option previously was not used here except for the case of printing version info.
* subversion/svn/svn.c Let 'help' take the '-v' option.
* subversion/tests/cmdline/getopt_tests_data/svn_help_stdout * subversion/tests/cmdline/getopt_tests_data/svn--help_stdout Adjust the expected output.
* tools/dist/backport.pl [Accidental change; reverted in 1866189.]