Remove i386_elf_emit_arch_note

Remove i386_elf_emit_arch_note

This x86 assembler patch:

https://sourceware.org/ml/binutils/2001-11/msg00344.html

generates a .note section for .arch directive so that GDB can tell which
architecture an i386 binary belongs:

https://sourceware.org/ml/binutils/2001-11/msg00271.html

However, x86 assembly code can have any instructions.  A .note section
doesn't help.  This patch removes it.

gas/

	* config/tc-i386.c (i386_elf_emit_arch_note): Removed.
	* config/tc-i386.h (md_end): Likewise.
	(i386_elf_emit_arch_note): Likewise.

gas/testsuite/

	* gas/i386/i386.exp: Run note.
	* gas/i386/note.d: New file.
	* gas/i386/note.s: Likewise.