PR breakpoints/17000: user breakpoint not inserted if software-single-step at same location - test

GDB gets confused when removing a software single-step breakpoint that
is at the same address as another breakpoint.  Add a kfailed test.

gdb/testsuite/
2014-05-30  Pedro Alves  <palves@redhat.com>

	PR breakpoints/17000
	* gdb.base/sss-bp-on-user-bp.c: New file.
	* gdb.base/sss-bp-on-user-bp.exp: New file.