S390: Support new vector register sections

S390: Support new vector register sections

The IBM z13 has new 128-bit wide vector registers v0-v31, where v0-v15
include the existing 64-bit wide floating point registers.  The Linux
kernel presents the vector registers as two additional register sets,
one for the right halves of v0-v15 and another one for the full
registers v16-v31.  Thus a new core file may contain two new register
note sections, and this patch adds support to binutils for them.

bfd/
	* elf-bfd.h (elfcore_write_s390_vxrs_low): Add prototype.
	(elfcore_write_s390_vxrs_high): Likewise.
	* elf.c (elfcore_grok_s390_vxrs_low): New function.
	(elfcore_grok_s390_vxrs_high): New function.
	(elfcore_grok_note): Call them.
	(elfcore_write_s390_vxrs_low): New function.
	(elfcore_write_s390_vxrs_high): New function.
	(elfcore_write_register_note): Call them.

binutils/
	* readelf.c (get_note_type): Add NT_S390_VXRS_LOW and
	NT_S390_VXRS_HIGH.

include/elf/
	* common.h (NT_S390_VXRS_LOW): New macro.
	(NT_S390_VXRS_HIGH): Likewise.