Stop using the __ANDROID_API_x__ constants.

Historically we've made a few mistakes where they haven't matched the
right number. And most non-Googlers are much more familiar with the
numbers, so it seems to make sense to rely more on them. Especially in
header files, which we actually expect real people to have to read from
time to time.

Test: treehugger
Change-Id: I0d4a97454ee108de1d32f21df285315c5488d886
diff --git a/libc/include/bits/fortify/poll.h b/libc/include/bits/fortify/poll.h
index 30fdce4..143153c 100644
--- a/libc/include/bits/fortify/poll.h
+++ b/libc/include/bits/fortify/poll.h
@@ -44,7 +44,7 @@
     __overloadable
     __clang_error_if(__bos_unevaluated_lt(__bos(fds), sizeof(*fds) * fd_count),
                      "in call to 'poll', fd_count is larger than the given buffer") {
-#if __ANDROID_API__ >= __ANDROID_API_M__ && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
+#if __ANDROID_API__ >= 23 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
   size_t bos_fds = __bos(fds);
 
   if (!__bos_fd_count_trivially_safe(bos_fds, fds, fd_count)) {
@@ -54,13 +54,13 @@
   return __call_bypassing_fortify(poll)(fds, fd_count, timeout);
 }
 
-#if __ANDROID_API__ >= __ANDROID_API_L__
+#if __ANDROID_API__ >= 21
 __BIONIC_FORTIFY_INLINE
 int ppoll(struct pollfd* const fds __pass_object_size, nfds_t fd_count, const struct timespec* timeout, const sigset_t* mask)
     __overloadable
     __clang_error_if(__bos_unevaluated_lt(__bos(fds), sizeof(*fds) * fd_count),
                      "in call to 'ppoll', fd_count is larger than the given buffer") {
-#if __ANDROID_API__ >= __ANDROID_API_M__ && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
+#if __ANDROID_API__ >= 23 && __BIONIC_FORTIFY_RUNTIME_CHECKS_ENABLED
   size_t bos_fds = __bos(fds);
 
   if (!__bos_fd_count_trivially_safe(bos_fds, fds, fd_count)) {
@@ -69,9 +69,9 @@
 #endif
   return __call_bypassing_fortify(ppoll)(fds, fd_count, timeout, mask);
 }
-#endif /* __ANDROID_API__ >= __ANDROID_API_L__ */
+#endif /* __ANDROID_API__ >= 21 */
 
-#if __ANDROID_API__ >= __ANDROID_API_P__
+#if __ANDROID_API__ >= 28
 __BIONIC_FORTIFY_INLINE
 int ppoll64(struct pollfd* const fds __pass_object_size, nfds_t fd_count, const struct timespec* timeout, const sigset64_t* mask)
     __overloadable
@@ -86,7 +86,7 @@
 #endif
   return __call_bypassing_fortify(ppoll64)(fds, fd_count, timeout, mask);
 }
-#endif /* __ANDROID_API__ >= __ANDROID_API_P__ */
+#endif /* __ANDROID_API__ >= 28 */
 
 #undef __bos_fd_count_trivially_safe