[MTE] Add a HWASan-style tag dump to tombstones.

We already dump the tags in the regigster dump section by appending the
tag to the memory address. You only get 2 granules before each register
and 13 after.

The HWASan-style tag dump is extremely useful for debugging, as it gives
a pretty comprehensive overview of the memory subsystem. It also
provides enough context bytes (256) to give you a reasonable intuition
about a particular bug.

The tag dump shows up only if PTRACE_PEEKTAGS returns at least one value
in the 256 requested. If the start of end of the region is untagged,
it's omitted. The tag dump looks like this:

Change-Id: Icc33fb97542d9b1fa3ae9e58aba34d524c6ba7b5

---
Memory tags around the fault address (0x60000704414d340), one tag per 16 bytes:
      0x704414d000: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d100: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d200: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
    =>0x704414d300: 0  0  0  0 [2] 2  0  0  0  0  0  0  0  0  0  0
      0x704414d400: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d500: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d600: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d700: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d800: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414d900: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
      0x704414da00: 0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
---

Bug: 183992164
Test: atest debuggerd_test on MTE+QEMU and sunfish.

Change-Id: I8d5842e4803ca30b407e866c99eef56f2cb36600
Merged-In: I8d5842e4803ca30b407e866c99eef56f2cb36600