Pass a valid stack pointer to __bionic_clone in pthread.__bionic_clone

__bionic_clone modifies the child stack before cloning so the stack
pointer should be valid. The test is expecting an EINVAL error to be
generated from the incorrect flags: CLONE_THREAD set without
CLONE_SIGHAND.

Change-Id: Ic02192081f6f52df6f03d9810efa82d923247a11
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index e7a952a..bcef566 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -251,7 +251,7 @@
   // Check that our hand-written clone assembler sets errno correctly on failure.
   uintptr_t fake_child_stack[16];
   errno = 0;
-  ASSERT_EQ(-1, __bionic_clone(CLONE_THREAD, &fake_child_stack[0], NULL, NULL, NULL, NULL, NULL));
+  ASSERT_EQ(-1, __bionic_clone(CLONE_THREAD, &fake_child_stack[16], NULL, NULL, NULL, NULL, NULL));
   ASSERT_EQ(EINVAL, errno);
 }
 #endif