gdb/

gdb/
	Fix attaching to PIEs prelinked on the disk after the process was
	started.
	* solib-svr4.c (svr4_exec_displacement): New variable arch_size.
	Verify it against bfd_get_arch_size.  Try to match arbitrary
	displacement for the phdrs comparison.

gdb/testsuite/
	* gdb.base/break-interp.exp: Run $binpie with new value "ATTACH", new
	code for it.  New variable relink_args.
	(prelinkYES): Call prelinkNO.
	(test_attach): Accept new parameter relink_args.  Re-prelink the binary
	in such case.  Move the core code to ...
	(test_attach_gdb): ... a new function.  Send GDB command "file".
	Extend expected "Attaching to " string.