* mmo.c: Correct and improve comments.

	* mmo.c: Correct and improve comments.
	(mmo_write_chunk): Store trailing byte in bfd buffer; don't
	zero-pad.  Use input to fill up non-empty bfd buffer.
	(mmo_flush_chunk): New function.
	(mmo_write_loc_chunk): Add parameter last_vmap, all callers
	changed.  Don't emit location specifier if VMA is same as
	*LAST_VMAP after omitting leading zero contents.  Call
	mmo_flush_chunk before emitting location specifier.
	(mmo_write_loc_chunk_list): Call mmo_flush_chunk when finished
	with mmo_write_loc_chunk calls.
	(mmo_internal_write_section): Call mmo_flush_chunk after
	mmo_write_chunk.
	(mmo_write_symbols_and_terminator): Move :Main to first position
	in symbol array.  Add faked one if it does not exist if there are
	other symbols.  Don't add it if there are no symbols at all.  Move
	out test for value of :Main from symbol loop.  Rename table
	fakemain to maintable and variable mainsym to fakemain.