[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
diff --git a/debuggerd/proto/tombstone.proto b/debuggerd/proto/tombstone.proto
index 22fc30e..a701212 100644
--- a/debuggerd/proto/tombstone.proto
+++ b/debuggerd/proto/tombstone.proto
@@ -56,8 +56,11 @@
 
   bool has_fault_address = 8;
   uint64 fault_address = 9;
+  // Note, may or may not contain the dump of the actual memory contents. Currently, on arm64, we
+  // only include metadata, and not the contents.
+  MemoryDump fault_adjacent_metadata = 10;
 
-  reserved 10 to 999;
+  reserved 11 to 999;
 }
 
 message HeapObject {
@@ -142,14 +145,22 @@
   reserved 9 to 999;
 }
 
+message ArmMTEMetadata {
+  // One memory tag per granule (e.g. every 16 bytes) of regular memory.
+  bytes memory_tags = 1;
+  reserved 2 to 999;
+}
+
 message MemoryDump {
   string register_name = 1;
   string mapping_name = 2;
   uint64 begin_address = 3;
   bytes memory = 4;
-  bytes tags = 5;
+  oneof metadata {
+    ArmMTEMetadata arm_mte_metadata = 6;
+  }
 
-  reserved 6 to 999;
+  reserved 5, 7 to 999;
 }
 
 message MemoryMapping {