Remove the always-true __INTRODUCED_IN() annotations.

The NDK no longer supports API levels earlier than 21.

This *doesn't* include <ctype.h> because I have a separate change
rewriting that (that's blocked on the upcoming libc++ update).

Test: treehugger
Change-Id: I53e915f27011dfc0513e0c78d8799377e183ceca
diff --git a/libc/include/sys/inotify.h b/libc/include/sys/inotify.h
index e834d07..f070857 100644
--- a/libc/include/sys/inotify.h
+++ b/libc/include/sys/inotify.h
@@ -41,7 +41,7 @@
 #define IN_NONBLOCK O_NONBLOCK
 
 int inotify_init(void);
-int inotify_init1(int __flags) __INTRODUCED_IN(21);
+int inotify_init1(int __flags);
 int inotify_add_watch(int __fd, const char* _Nonnull __path, uint32_t __mask);
 int inotify_rm_watch(int __fd, uint32_t __watch_descriptor);