Stop #define'ing __ANDROID_API__.

Also normalize the non-bionic definitions of __INTRODUCED_IN() to match
the majority.

Bug: http://b/178449269
Test: treehugger
Change-Id: I378a6d8a01999958f397c896a375d38a9de43f8f
diff --git a/include/android/bitmap.h b/include/android/bitmap.h
index 2362c9e..a70dffd 100644
--- a/include/android/bitmap.h
+++ b/include/android/bitmap.h
@@ -31,18 +31,8 @@
 #include <stddef.h>
 #include <jni.h>
 
-#ifndef __ANDROID__
-    // Value copied from 'bionic/libc/include/android/api-level.h' which is not available on
-    // non Android systems. It is set to 10000 which is same as __ANDROID_API_FUTURE__ value.
-    #ifndef __ANDROID_API__
-        #define __ANDROID_API__ 10000
-    #endif
-
-    // Value copied from 'bionic/libc/include/android/versioning.h' which is not available on
-    // non Android systems
-    #ifndef __INTRODUCED_IN
-        #define __INTRODUCED_IN(api_level)
-    #endif
+#if !defined(__INTRODUCED_IN)
+#define __INTRODUCED_IN(__api_level) /* nothing */
 #endif
 
 #ifdef __cplusplus