Don't corrupt the thread list in static executables.

Several previous changes conspired to make a mess of the thread list
in static binaries. This was most obvious when trying to call
pthread_key_delete(3) on the main thread.

Bug: http://code.google.com/p/android/issues/detail?id=36893
Change-Id: I2a2f553114d8fb40533c481252b410c10656da2e

tests/pthread_test.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include <errno.h>
+#include <pthread.h>
+
+TEST(pthread, pthread_key_create) {
+  pthread_key_t key;
+  ASSERT_EQ(0, pthread_key_create(&key, NULL));
+  ASSERT_EQ(0, pthread_key_delete(key));
+  // Can't delete a key that's already been deleted.
+  ASSERT_EQ(EINVAL, pthread_key_delete(key));
+}