LTO plugin: use startswith function.

LTO plugin: use startswith function.

lto-plugin/ChangeLog:

	* lto-plugin.c (LTO_SEGMENT_NAME): Remove.
	(LTO_SYMTAB_PREFIX): Likewise.
	(LTO_SYMTAB_PREFIX_LEN): Likewise.
	(LTO_SYMTAB_EXT_PREFIX): Likewise.
	(LTO_SYMTAB_EXT_PREFIX_LEN): Likewise.
	(LTO_LTO_PREFIX): Likewise.
	(LTO_LTO_PREFIX_LEN): Likewise.
	(OFFLOAD_SECTION): Likewise.
	(OFFLOAD_SECTION_LEN): Likewise.
	(startswith): New function.
	(all_symbols_read_handler): Use it.
	(process_symtab): Likewise.
	(process_symtab_extension): Likewise.
	(process_offload_section): Likewise.
	(process_option): Likewise.