Remove argument pc in get_next_pcs

Remove argument pc in get_next_pcs

Nowadays, get_next_pcs in linux_target_ops has two parameters PC
and REGCACHE.  Parameter PC looks redundant because it can be go
from REGCACHE.  The patch is to remove PC from the arguments for
various functions.

gdb:

2016-01-26  Yao Qi  <yao.qi@linaro.org>

	* arch/arm-get-next-pcs.c (thumb_deal_with_atomic_sequence_raw):
	Remove argument pc.  Get pc by regcache_read_pc.  Callers updated.
	(arm_deal_with_atomic_sequence_raw): Likewise.
	(thumb_get_next_pcs_raw): Likewise.
	(arm_get_next_pcs_raw): Likewise.
	(arm_get_next_pcs): Remove argument pc.  Callers updated.
	* arch/arm-get-next-pcs.h (arm_get_next_pcs): Update declaration.

gdb/gdbserver:

2016-01-26  Yao Qi  <yao.qi@linaro.org>

	* linux-arm-low.c (arm_gdbserver_get_next_pcs): Remove argument pc.
	* linux-low.c (install_software_single_step_breakpoints): Don't
	call regcache_read_pc.
	* linux-low.h (struct linux_target_ops) <get_next_pcs>: Remove
	argument pc.