[binutils-gdb] x86-64: fix ZMM register state tracking

[sergiodj+buildbot at sergiodj dot net]

*** TEST RESULTS FOR COMMIT b5420128da08dc81d94b265e88083d172909ea25 ***

Author: Jan Beulich <jbeulich@novell.com>
Branch: master
Commit: b5420128da08dc81d94b265e88083d172909ea25

x86-64: fix ZMM register state tracking

The three AVX512 state components are entirely independent - one being
in its "init state" has no implication whatsoever on either of the other
two. Fully separate X86_XSTATE_ZMM_H and X86_XSTATE_ZMM handling, to
prevent upper halves of the upper 16 ZMM registers to display as if they
were zero (when they aren't) after e.g. VZEROALL/VZEROUPPER.