Fix for remote G Packet message too long error for baremetal.

Prior to version MicroBlaze v8.10.a,EDK 13.1, XMD's gdbserver stub returned 57
registers in response to GDB's G request. Starting with version MicroBlaze
v8.10.a, EDK 13.1, XMD added the slr and shr register, for a count of 59
registers. This patch adds these registers to the expected G response. This patch
fixes the above problem for baremetal and also supports the backward compatibility.

ChangeLog:
2014-07-02  Ajit Agarwal  <ajitkum@xilinx.com>

	* microblaze-tdep.c (microblaze_register_names): Add
	the rshr and rslr register names.
	(microblaze_gdbarch_init): Use of tdesc_has_registers.
	Use of tdesc_find_feature. Use of tdesc_data_alloc.
	Use of tdesc_numbered_register. Use of
	microblaze_register_g_packet_guesses. Use of
	tdesc_use_registers. Use of set_gdbarch_register_type.
	(microblaze_register_g_packet_guesses): New.
	* microblaze-tdep.h (microblaze_reg_num): Add
	field MICROBLAZE_SLR_REGNUM MICROBLAZE_SHR_REGNUM
	MICROBLAZE_NUM_REGS and MICROBLAZE_NUM_CORE_REGS.
	(microblaze_frame_cache): Use of MICROBLAZE_NUM_REGS.
	* features/microblaze-core.xml: New file.
	* features/microblaze-stack-protect.xml: New file.
	* features/microblaze-with-stack-protect.c: New file.
	* features/microblaze-with-stack-protect.xml: New file.
	* features/microblaze.xml: New file.
	* features/microblaze.c: New file.
	* features/Makefile (microblaze-with-stack-protect): Add
	microblaze-with-stack-protect microblaze and
	microblaze-expedite.
	* regformats/microblaze-with-stack-protect.dat: New file.
	* regformats/microblaze.dat: New file.
	* doc/gdb.texinfo (MicroBlaze Features): New.

Signed-off-by: Ajit Agarwal <ajitkum@xilinx.com>