A little bit more of the threads implementation.

The most important change here is understanding that Thread's id_ field
was unrelated to java.lang.Thread's id field.

Change-Id: I832b92145332e1ded63a7824033dae684eeacf28
diff --git a/src/utils.h b/src/utils.h
index 69ca168..78d655e 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -180,6 +180,10 @@
 // Returns the calling thread's tid. (The C libraries don't expose this.)
 pid_t GetTid();
 
+// Sets the name of the current thread. The name may be truncated to an
+// implementation-defined limit.
+void SetThreadName(const char* name);
+
 }  // namespace art
 
 #endif  // ART_SRC_UTILS_H_