Use async safe logging in signal handlers.

Test: Boot on bullhead.
Test: Ran the libbacktrace tests on bullhead.
Test: Added a temporary log message in the signal handler, and ran the
Test: backtrace tests.
Change-Id: I0a6888c9f311af2c8cc7fbb4929315911bd2bb3c
diff --git a/libbacktrace/ThreadEntry.cpp b/libbacktrace/ThreadEntry.cpp
index 084c1aa..9bd59e4 100644
--- a/libbacktrace/ThreadEntry.cpp
+++ b/libbacktrace/ThreadEntry.cpp
@@ -21,7 +21,7 @@
 #include <time.h>
 #include <ucontext.h>
 
-#include "BacktraceLog.h"
+#include "BacktraceAsyncSafeLog.h"
 #include "ThreadEntry.h"
 
 // Initialize static member variables.
@@ -106,7 +106,7 @@
   while (wait_value_ != value) {
     int ret = pthread_cond_timedwait(&wait_cond_, &wait_mutex_, &ts);
     if (ret != 0) {
-      BACK_LOGW("pthread_cond_timedwait for value %d failed: %s", value, strerror(ret));
+      BACK_ASYNC_SAFE_LOGW("pthread_cond_timedwait for value %d failed: %s", value, strerror(ret));
       wait_completed = false;
       break;
     }