Update more calls to add_prefix_cmd

Update more calls to add_prefix_cmd

I looked at all the calls to add_prefix_cmd, and replaced them with
calls to add_basic_prefix_cmd or add_show_prefix_cmd when appropriate.
This makes gdb's command language a bit more regular.  I don't think
there's a significant downside.

Note that this patch removes a couple of tests.  The removed ones are
completely redundant.

gdb/ChangeLog
2020-05-03  Tom Tromey  <tom@tromey.com>

	* breakpoint.c (catch_command, tcatch_command): Remove.
	(_initialize_breakpoint): Use add_basic_prefix_cmd,
	add_show_prefix_cmd.
	(set_breakpoint_cmd, show_breakpoint_cmd): Remove
	* utils.c (set_internal_problem_cmd, show_internal_problem_cmd):
	Remove.
	(add_internal_problem_command): Use add_basic_prefix_cmd,
	add_show_prefix_cmd.
	* mips-tdep.c (set_mipsfpu_command): Remove.
	(_initialize_mips_tdep): Use add_basic_prefix_cmd.
	* dwarf2/index-cache.c (set_index_cache_command): Remove.
	(_initialize_index_cache): Use add_basic_prefix_cmd.
	* memattr.c (dummy_cmd): Remove.
	(_initialize_mem): Use add_basic_prefix_cmd, add_show_prefix_cmd.
	* tui/tui-win.c (set_tui_cmd, show_tui_cmd): Remove.
	(_initialize_tui_win): Use add_basic_prefix_cmd,
	add_show_prefix_cmd.
	* cli/cli-logging.c (set_logging_command): Remove.
	(_initialize_cli_logging): Use add_basic_prefix_cmd,
	add_show_prefix_cmd.
	(show_logging_command): Remove.
	* target.c (target_command): Remove.
	(add_target): Use add_basic_prefix_cmd.

gdb/testsuite/ChangeLog
2020-05-03  Tom Tromey  <tom@tromey.com>

	* gdb.base/sepdebug.exp: Remove "catch" test.
	* gdb.base/break.exp: Remove "catch" test.
	* gdb.base/default.exp: Update expected output.