fix gdb.arch to be parallel-safe

fix gdb.arch to be parallel-safe

This fixes parts of gdb.arch to be parallel-safe.
I only changed the bits I could test on this machine.

I don't have access to many of the machines needed to fully switch
gdb.arch; but I am happy to provide advice to others attempting this.
Or, I can send an untested patch to convert it all.

Tested on x86-64 Fedora 18.

	* gdb.arch/amd64-byte.exp: Use standard_testfile,
	clean_restart.
	* gdb.arch/amd64-disp-step.exp: Use standard_testfile.
	* gdb.arch/amd64-dword.exp: Use standard_testfile,
	clean_restart.
	* gdb.arch/amd64-entry-value-param.exp: Use standard_testfile.
	* gdb.arch/amd64-entry-value.exp: Use standard_testfile.
	* gdb.arch/amd64-prologue-xmm.exp: Use standard_testfile.
	* gdb.arch/amd64-word.exp: Use standard_testfile,
	clean_restart.
	* gdb.arch/i386-avx.exp: Use standard_testfile, clean_restart.
	* gdb.arch/i386-byte.exp: Use standard_testfile, clean_restart.
	* gdb.arch/i386-disp-step.exp: Use standard_testfile.
	* gdb.arch/i386-dr3-watch.exp: Use standard_testfile.
	* gdb.arch/i386-permbkpt.exp: Use standard_testfile, clean_restart.
	* gdb.arch/i386-signal.exp: Use standard_testfile.
	* gdb.arch/i386-size-overlap.exp: Use standard_testfile, clean_restart.
	* gdb.arch/i386-sse.exp: Use standard_testfile, clean_restart.
	* gdb.arch/i386-unwind.exp: Use standard_testfile.
	* gdb.arch/i386-word.exp: Use standard_testfile, clean_restart.