Add __INTRODUCED_IN to core <android/*.h> APIs.

Bug: https://github.com/android-ndk/ndk/issues/706
Bug: http://b/113052379
Test: builds
Change-Id: I23db5a2180517045bafabe6fbf783456cbddf21a
(cherry picked from commit 9db409b053460e065cefb1d1caefe048f90cfff0)
diff --git a/include/android/sharedmem_jni.h b/include/android/sharedmem_jni.h
index 2af3955..5abc245 100644
--- a/include/android/sharedmem_jni.h
+++ b/include/android/sharedmem_jni.h
@@ -51,8 +51,6 @@
 extern "C" {
 #endif
 
-#if __ANDROID_API__ >= __ANDROID_API_O_MR1__
-
 /**
  * Returns a dup'd FD from the given Java android.os.SharedMemory object. The returned file
  * descriptor has all the same properties & capabilities as the FD returned from
@@ -69,9 +67,7 @@
  *      already closed, if the JNIEnv or jobject is NULL, or if there are too many open file
  *      descriptors (errno=EMFILE)
  */
-int ASharedMemory_dupFromJava(JNIEnv* env, jobject sharedMemory);
-
-#endif
+int ASharedMemory_dupFromJava(JNIEnv* env, jobject sharedMemory) __INTRODUCED_IN(27);
 
 #ifdef __cplusplus
 };