Remove "private/bionic_pthread.h".

Bug: 17476168
Change-Id: Id642987e641de81e914a28daea4ffe9d11e090ed
diff --git a/libc/bionic/ndk_cruft.cpp b/libc/bionic/ndk_cruft.cpp
index 829e8f3..2cd2e33 100644
--- a/libc/bionic/ndk_cruft.cpp
+++ b/libc/bionic/ndk_cruft.cpp
@@ -320,4 +320,9 @@
   return malloc_usable_size(ptr);
 }
 
+// In L we added a public pthread_gettid_np, but some apps were using the private API.
+extern "C" pid_t __pthread_gettid(pthread_t t) {
+  return pthread_gettid_np(t);
+}
+
 #endif