Clear addr bit in next_pcs vector

Clear addr bit in next_pcs vector

This patch is to split the loop of calling gdbarch_addr_bits_remove
and insert_single_step_breakpoint into two loops.

gdb:

2016-11-08  Yao Qi  <yao.qi@linaro.org>

	* arm-linux-tdep.c (arm_linux_software_single_step): Write
	adjusted address back to vector.  Call insert_single_step_breakpoint
	in a new loop.
	* arm-tdep.c (arm_software_single_step): Likewise.