[ppc64] Add POWER8/ISA 2.07 atomic sequences single-stepping support

[ppc64] Add POWER8/ISA 2.07 atomic sequences single-stepping support

gdb/
2017-02-21  Edjunior Barbosa Machado  <emachado@linux.vnet.ibm.com>

	* rs6000-tdep.c (LOAD_AND_RESERVE_MASK): Rename from LWARX_MASK.
	(STORE_CONDITIONAL_MASK): Rename from STWCX_MASK.
	(LBARX_INSTRUCTION, LHARX_INSTRUCTION, LQARX_INSTRUCTION,
	STBCX_INSTRUCTION, STHCX_INSTRUCTION, STQCX_INSTRUCTION): New defines.
	(IS_LOAD_AND_RESERVE_INSN, IS_STORE_CONDITIONAL_INSN): New macros.
	(ppc_displaced_step_copy_insn): Use IS_LOAD_AND_RESERVE_INSN.
	(ppc_deal_with_atomic_sequence): Use IS_LOAD_AND_RESERVE_INSN and
	IS_STORE_CONDITIONAL_INSN.

gdb/testsuite/
2017-02-21  Edjunior Barbosa Machado  <emachado@linux.vnet.ibm.com>

	* gdb.arch/ppc64-isa207-atomic-inst.exp: New testcase based on
	gdb.arch/ppc64-atomic-inst.exp.  Add tests for lbarx/stbcx, lharx/sthcx
	and lqarx/stqcx.
	* gdb.arch/ppc64-isa207-atomic-inst.S: New file.
	* gdb.arch/ppc64-isa207-atomic-inst.c: Likewise.