AArch64: Report tag violation error information

AArch64: Report tag violation error information

Whenever a memory tag violation occurs, we get a SIGSEGV. Additional
information can be obtained through the siginfo data structure.

For AArch64 the Linux kernel may expose the fault address and tag
information, if we have a synchronous event. Otherwise there is
no fault address available.

The synchronous event looks like this:

--
(gdb) continue
Continuing.

Program received signal SIGSEGV, Segmentation fault
Memory tag violation while accessing address 0x0500fffff7ff8000
Allocation tag 0x1.
Logical tag 0x5
--

The asynchronous event looks like this:

--
(gdb) continue
Continuing.

Program received signal SIGSEGV, Segmentation fault
Memory tag violation
Fault address unavailable.
--

gdb/ChangeLog:

2021-03-24  Luis Machado  <luis.machado@linaro.org>

	* aarch64-linux-tdep.c
	(aarch64_linux_report_signal_info): New function.
	(aarch64_linux_init_abi): Register
	aarch64_linux_report_signal_info as the report_signal_info hook.
	* arch/aarch64-linux.h (SEGV_MTEAERR): Define.
	(SEGV_MTESERR): Define.