Add and use constants for the Android API levels.

Test: bionic tests still pass
Change-Id: If1b619cfc9db1d3f5d91f14f2ace71058dca0c4a
diff --git a/libc/include/android/legacy_fenv_inlines_arm.h b/libc/include/android/legacy_fenv_inlines_arm.h
index a5bb26b..58c49c2 100644
--- a/libc/include/android/legacy_fenv_inlines_arm.h
+++ b/libc/include/android/legacy_fenv_inlines_arm.h
@@ -31,7 +31,7 @@
 
 #include <fenv.h>
 
-#if __ANDROID_API__ < 21 && defined(__arm__)
+#if __ANDROID_API__ < __ANDROID_API_L__ && defined(__arm__)
 
 __BEGIN_DECLS
 
@@ -149,6 +149,6 @@
 
 __END_DECLS
 
-#endif /* __ANDROID_API__ < 21 && defined(__arm__) */
+#endif /* __ANDROID_API__ < __ANDROID_API_L__ && defined(__arm__) */
 
 #endif /* ANDROID_LEGACY_FENV_INLINES_ARM_H */