Restore __ANDROID_API__ guards for core <android/*> APIs

This commit restores the __ANDROID_API__ guards removed in
"Add __INTRODUCED_IN to core <android/*.h> APIs.",
commit 9db409b053460e065cefb1d1caefe048f90cfff0.

Add a guard to surface_texture.h.

In choreographer.h, declare the types even for older APIs.

Bug: http://b/111668906
Test: builds
Change-Id: Ia013f48a109310f9f8ca6a3211f28fcb69dd602d
(cherry picked from commit 92b1ebea095f9cac70b81ae7382ae69583c9914d)
diff --git a/include/android/trace.h b/include/android/trace.h
index 9f59acf..4d57d4f 100644
--- a/include/android/trace.h
+++ b/include/android/trace.h
@@ -37,6 +37,8 @@
 extern "C" {
 #endif
 
+#if __ANDROID_API__ >= 23
+
 /**
  * Returns true if tracing is enabled. Use this signal to avoid expensive computation only necessary
  * when tracing is enabled.
@@ -61,6 +63,8 @@
  */
 void ATrace_endSection() __INTRODUCED_IN(23);
 
+#endif /* __ANDROID_API__ >= 23 */
+
 #ifdef __cplusplus
 };
 #endif