Add and use constants for the Android API levels.

Test: bionic tests still pass
Change-Id: If1b619cfc9db1d3f5d91f14f2ace71058dca0c4a
diff --git a/linker/linker_soinfo.cpp b/linker/linker_soinfo.cpp
index 59bdc4d..16e42c2 100644
--- a/linker/linker_soinfo.cpp
+++ b/linker/linker_soinfo.cpp
@@ -726,7 +726,7 @@
 }
 
 void* soinfo::to_handle() {
-  if (get_application_target_sdk_version() <= 23 || !has_min_version(3)) {
+  if (get_application_target_sdk_version() < __ANDROID_API_N__ || !has_min_version(3)) {
     return this;
   }
 
@@ -791,5 +791,3 @@
 
   return gnu_hash_;
 }
-
-