Remove libbacktrace definition of gettid.
Also simplifies the Darwin implementation of gettid, because
apparently libbacktrace had a better way of doing it.
Change-Id: I9e14f9176b167405a5aaa5b8a0db0327c7126271
diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index 91ca8b7..b2d8297 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -27,6 +27,8 @@
#include <backtrace/Backtrace.h>
#include <backtrace/BacktraceMap.h>
+#include <cutils/threads.h>
+
#include "BacktraceLog.h"
#include "thread_utils.h"
#include "UnwindCurrent.h"