Check for data races when reading JIT/DEX entries.

Update the entries only when the list is modified by the runtime.

Check that the list wasn't concurrently modified when being read.

Bug: 124287208
Test: libunwindstack_test
Test: art/test.py -b --host -r -t 137-cfi
Change-Id: I87ba70322053a01b3d5be1fdf6310e1dc21bb084
diff --git a/debuggerd/crash_dump.cpp b/debuggerd/crash_dump.cpp
index 82ba0a1..437450c 100644
--- a/debuggerd/crash_dump.cpp
+++ b/debuggerd/crash_dump.cpp
@@ -48,7 +48,6 @@
 #define ATRACE_TAG ATRACE_TAG_BIONIC
 #include <utils/Trace.h>
 
-#include <unwindstack/DexFiles.h>
 #include <unwindstack/JitDebug.h>
 #include <unwindstack/Maps.h>
 #include <unwindstack/Memory.h>
@@ -567,7 +566,7 @@
 
   // TODO: Use seccomp to lock ourselves down.
   unwindstack::UnwinderFromPid unwinder(256, vm_pid);
-  if (!unwinder.Init(unwindstack::Regs::CurrentArch())) {
+  if (!unwinder.Init()) {
     LOG(FATAL) << "Failed to init unwinder object.";
   }