Hi,

This patch introduces ETE (Embedded Trace Extension) system registers.
If ETE is implemented, the ETE registers are:
- TRCEXTINSELR<0-3> an External Input Select Register <n>.
- TRCRSR            a Resources Status Register.

Above system registers are documented here:
https://developer.arm.com/docs/ddi0601/f

Note: as this is register only extension, we do not want to hide these
registers behind -march flag going forward (they should be enabled by
default).

aarch64-none-linux-gnu binutils regression tests OK.

OK for master branch?

PS: I do not have write permission, can this be commited in my name if
approved please?

Kind regards,
Przemyslaw Wirkus

gas/ChangeLog:

2020-09-17  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>

              * testsuite/gas/aarch64/ete.d: New test.
              * testsuite/gas/aarch64/ete.s: New test.

opcodes/ChangeLog:

2020-09-17  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>

              * aarch64-opc.c: Add ETE system registers TRCEXTINSELR<0-3> and TRCRSR.