gdb.trace/entry-values.exp: Fixes for powerpc64.

gdb.trace/entry-values.exp: Fixes for powerpc64.

On powerpc64, "disassemble foo" doesn't work properly on object files
(it can't process the relocations in .opd section) - instead, let's
link it into an executable and load that.

Also, backtrace displays .main, not main.  Accept both.

gdb/testsuite/ChangeLog:

	* gdb.trace/entry-values.exp: Link ${binfile}1.o to ${binfile}1 and
	use it for disassembly; accept .main in addition to main in backtrace.