gdb/

gdb/
	* s390-nat.c (s390_can_use_hw_breakpoint): Only support breakpoints
	of type bp_hardware_watchpoint.

gdb/testsuite/

	* gdb.base/hbreak.exp: Disable for s390*-*-* targets.
	* gdb.base/watchpoint-hw-hit-once.exp: Likewise.
	* gdb.threads/watchthreads-reorder.exp: Likewise.