Update for accurate unreadable elf files.

The functionality moved from the Unwinder object to the MapInfo
object and means that the individual unreadable files can be
displayed now.

Included adding the unreadable elfs per thread in the protobuf.

Updated the unwinder test.

Test: All unit tests pass.
Change-Id: I7140bde16938736da005f926e10bbdb3dbc0f6f5
diff --git a/debuggerd/proto/tombstone.proto b/debuggerd/proto/tombstone.proto
index 40a942e..a0f2f82 100644
--- a/debuggerd/proto/tombstone.proto
+++ b/debuggerd/proto/tombstone.proto
@@ -123,12 +123,13 @@
   string name = 2;
   repeated Register registers = 3;
   repeated string backtrace_note = 7;
+  repeated string unreadable_elf_files = 9;
   repeated BacktraceFrame current_backtrace = 4;
   repeated MemoryDump memory_dump = 5;
   int64 tagged_addr_ctrl = 6;
   int64 pac_enabled_keys = 8;
 
-  reserved 9 to 999;
+  reserved 10 to 999;
 }
 
 message BacktraceFrame {