Now that the -info-gdb-mi-command is available, there is no need for
this entry. The entry and associated new commands were added recently
enough that no front-end out there should be depending on it yet.
gdb/ChangeLog:
* mi/mi-main.c (mi_cmd_list_features): Remove "ada-exceptions".
gdb/doc/ChangeLog:
* gdb.texinfo (GDB/MI Miscellaneous Commands): Remove the
documentation of the "ada-exceptions" entry.