Add and use constants for the Android API levels.

Test: bionic tests still pass
Change-Id: If1b619cfc9db1d3f5d91f14f2ace71058dca0c4a
diff --git a/libc/bionic/semaphore.cpp b/libc/bionic/semaphore.cpp
index 1981647..610a1b2 100644
--- a/libc/bionic/semaphore.cpp
+++ b/libc/bionic/semaphore.cpp
@@ -222,7 +222,7 @@
     }
 
     int result = __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, false, nullptr);
-    if (bionic_get_application_target_sdk_version() > 23) {
+    if (bionic_get_application_target_sdk_version() >= __ANDROID_API_N__) {
       if (result ==-EINTR) {
         errno = EINTR;
         return -1;