(SET_TEXINPUTS): Add $(GDBMI_DIR).
(SFILES_DOC): Add $(GDBMI_DIR)/gdbmi.texinfo.
(gdbmi.texinfo): New target, for texi2roff.
(gdb.me, gdb.ms, gdb.mm): Depend on gdbmi.texinfo.
(gdb.info, gdb_toc.html): Add "-I ${GDBMI_DIR}".
* gdb.texinfo (Top): Add GDB/MI to the main menu and @include
gdbmi.texinfo.
(Mode Options): Add xref to GDB/MI docs and remove a FIXME
comment.
* gdbmi.texinfo: Lots of changes, to include this document as part
of the GDB manual.
* TODO, NEWS: Update due to inclusion of gdbmi.texinfo in the GDB
manual.
