* symfile.c (section_is_mapped): Use objfile architecture instead

	* symfile.c (section_is_mapped): Use objfile architecture instead
	of current_gdbarch.
	(TARGET_LONG_BYTES): Remove.
	(read_target_long_array): Add SIZE argument.  Use it instead of
	TARGET_LONG_BYTES.
	(simple_read_overlay_table): Retrieve long size from objfile
	architecture; pass it to read_target_long_array.
	(simple_read_overlay_region_table): Likewise.
	(simple_overlay_update_1): Likewise.