Fix typos in gold.

Fix typos in gold.

gold/:
	* dwarf_reader.cc: Remove outdated comment.
	* gold-threads.cc: Fix typo in error message.
	* archive.cc: Fix typos in comments.
	* archive.h: Likewise.
	* arm-reloc-property.cc: Likewise.
	* arm-reloc-property.h: Likewise.
	* arm-reloc.def: Likewise.
	* arm.cc: Likewise.
	* attributes.h: Likewise.
	* cref.cc: Likewise.
	* ehframe.cc: Likewise.
	* fileread.h: Likewise.
	* gold.h: Likewise.
	* i386.cc: Likewise.
	* icf.cc: Likewise.
	* incremental.h: Likewise.
	* int_encoding.cc: Likewise.
	* layout.h: Likewise.
	* main.cc: Likewise.
	* merge.h: Likewise.
	* object.cc: Likewise.
	* object.h: Likewise.
	* options.cc: Likewise.
	* readsyms.cc: Likewise.
	* reduced_debug_output.cc: Likewise.
	* reloc.cc: Likewise.
	* script-sections.cc: Likewise.
	* sparc.cc: Likewise.
	* symtab.h: Likewise.
	* target-reloc.h: Likewise.
	* target.cc: Likewise.
	* target.h: Likewise.
	* timer.cc: Likewise.
	* timer.h: Likewise.
	* x86_64.cc: Likewise.