gdb/mi: New commands to catch C++ exceptions

gdb/mi: New commands to catch C++ exceptions

Adds some MI commands to catch C++ exceptions.  The new commands are
-catch-throw, -catch-rethrow, and -catch-catch, these all correspond
to the CLI commands 'catch throw', 'catch rethrow', and 'catch catch'.

Each MI command takes two optional arguments, '-t' has the effect of
calling 'tcatch' instead of 'catch', for example:

   (gdb)
   -catch-throw -t

Is the same as:

   (gdb) tcatch throw

There is also a '-r REGEXP' argument that can supply a regexp to match
against the exception type, so:

   (gdb)
   -catch-catch -r PATTERN

Is the same as:

   (gdb) catch catch PATTERN

The change in print_mention_exception_catchpoint might seem a little
strange; changing the output from using ui_out::field_int and
ui_out::text to using  ui_out::message.

The print_mention_exception_catchpoint is used as the 'print_mention'
method for the exception catchpoint breakpoint object.  Most of the
other 'print_mention' methods (see breakpoint.c) use either
printf_filtered, of ui_out::message.  Using field_int was causing an
unexpected field to be added to the MI output.  Here's the output
without the change in print_mention_exception_catchpoint:

    (gdb)
    -catch-throw
    ^done,bkptno="1",bkpt={number="1",type="breakpoint",disp="keep",
                           enabled="y",addr="0x00000000004006c0",
                           what="exception throw",catch-type="throw",
                           thread-groups=["i1"],times="0"}

Notice the breakpoint number appears in both the 'bkptno' field, and
the 'number' field within the 'bkpt' tuple.  Here's the output with
the change in print_mention_exception_catchpoint:

    (gdb)
    -catch-throw
    ^done,bkpt={number="1",type="breakpoint",disp="keep",
                enabled="y",addr="0x00000000004006c0",
                what="exception throw",catch-type="throw",
                thread-groups=["i1"],times="0"}

gdb/ChangeLog:

	* NEWS: Mention new MI commands.
	* break-catch-throw.c (enum exception_event_kind): Move to
	breakpoint.h.
	(print_mention_exception_catchpoint): Output text as a single
	message.
	(catch_exception_command_1): Rename to...
	(catch_exception_event): ...this, make non-static, update header
	command, and change some parameter types.
	(catch_catch_command): Update for changes to
	catch_exception_command_1.
	(catch_throw_command): Likewise.
	(catch_rethrow_command): Likewise.
	* breakpoint.c (enum exception_event_kind): Delete.
	* breakpoint.h (enum exception_event_kind): Moved here from
	break-catch-throw.c.
	(catch_exception_event): Declare.
	* mi/mi-cmd-catch.c (mi_cmd_catch_exception_event): New function.
	(mi_cmd_catch_throw): New function.
	(mi_cmd_catch_rethrow): New function.
	(mi_cmd_catch_catch): New function.
	* mi/mi-cmds.c (mi_cmds): Add 'catch-throw', 'catch-rethrow', and
	'catch-catch' entries.
	* mi/mi-cmds.h (mi_cmd_catch_throw): Declare.
	(mi_cmd_catch_rethrow): Declare.
	(mi_cmd_catch_catch): Declare.

gdb/doc/ChangeLog:

	* gdb.texinfo (GDB/MI Catchpoint Commands): Add menu entry to new
	node.
	(C++ Exception GDB/MI Catchpoint Commands): New node to describe
	new MI commands.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-catch-cpp-exceptions.cc: New file.
	* gdb.mi/mi-catch-cpp-exceptions.exp: New file.
	* lib/mi-support.exp (mi_expect_stop): Handle 'exception-caught'
	as a stop reason.