New GDB/MI commands to catch Ada exceptions

New GDB/MI commands to catch Ada exceptions

This patch introduces two new GDB/MI commands implementing the equivalent
of the "catch exception" and  "catch assert" GDB/CLI commands.

gdb/ChangeLog:

        * breakpoint.h (init_ada_exception_breakpoint): Add parameter
        "enabled".
        * breakpoint.c (init_ada_exception_breakpoint): Add parameter
        "enabled".  Set B->ENABLE_STATE accordingly.
        * ada-lang.h (ada_exception_catchpoint_kind): Move here from
        ada-lang.c.
        (create_ada_exception_catchpoint): Add declaration.
        * ada-lang.c (ada_exception_catchpoint_kind): Move to ada-lang.h.
        (create_ada_exception_catchpoint): Make non-static. Add new
        parameter "disabled". Use it in call to
        init_ada_exception_breakpoint.
        (catch_ada_exception_command): Add parameter "enabled" in call
        to create_ada_exception_catchpoint.
        (catch_assert_command): Likewise.

        * mi/mi-cmds.h (mi_cmd_catch_assert, mi_cmd_catch_exception):
        Add declarations.
        * mi/mi-cmds.c (mi_cmds): Add the "catch-assert" and
        "catch-exception" commands.
        * mi/mi-cmd-catch.c: Add #include "ada-lang.h".
        (mi_cmd_catch_assert, mi_cmd_catch_exception): New functions.