Assume glibc >= 2.15.

This catches one trivial difference between us and glibc --- the error
returned by pthread_setname_np for an invalid pthread_t.

Change-Id: If4c21e22107c6488333d11184f8005f8669096c2
diff --git a/libc/bionic/pthread_setname_np.cpp b/libc/bionic/pthread_setname_np.cpp
index 7b2fa6b..93d4b2f 100644
--- a/libc/bionic/pthread_setname_np.cpp
+++ b/libc/bionic/pthread_setname_np.cpp
@@ -61,7 +61,7 @@
   {
     pthread_accessor thread(t);
     if (thread.get() == NULL) {
-      return ESRCH;
+      return ENOENT;
     }
     tid = thread->tid;
   }