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/search.h b/libc/include/search.h
index 00deef1..fe897d1 100644
--- a/libc/include/search.h
+++ b/libc/include/search.h
@@ -66,18 +66,14 @@
 /**
  * [insque(3)](http://man7.org/linux/man-pages/man3/insque.3.html) inserts
  * an item in a queue (an intrusive doubly-linked list).
- *
- * Available since API level 21.
  */
-void insque(void* _Nonnull __element, void* _Nullable __previous) __INTRODUCED_IN(21);
+void insque(void* _Nonnull __element, void* _Nullable __previous);
 
 /**
  * [remque(3)](http://man7.org/linux/man-pages/man3/remque.3.html) removes
  * an item from a queue (an intrusive doubly-linked list).
- *
- * Available since API level 21.
  */
-void remque(void* _Nonnull __element) __INTRODUCED_IN(21);
+void remque(void* _Nonnull __element);
 
 /**
  * [hcreate(3)](http://man7.org/linux/man-pages/man3/hcreate.3.html)
@@ -155,10 +151,8 @@
  * See bsearch() if you have a sorted array.
  *
  * Returns a pointer to the matching element on success, or NULL on failure.
- *
- * Available since API level 21.
  */
-void* _Nullable lfind(const void* _Nonnull __key, const void* _Nonnull __array, size_t* _Nonnull __count, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull, const void* _Nonnull)) __INTRODUCED_IN(21);
+void* _Nullable lfind(const void* _Nonnull __key, const void* _Nonnull __array, size_t* _Nonnull __count, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull, const void* _Nonnull));
 
 /**
  * [lsearch(3)](http://man7.org/linux/man-pages/man3/lsearch.3.html) brute-force
@@ -170,10 +164,8 @@
  *
  * Returns a pointer to the matching element on success, or to the newly-added
  * element on failure.
- *
- * Available since API level 21.
  */
-void* _Nonnull lsearch(const void* _Nonnull __key, void* _Nonnull __array, size_t* _Nonnull __count, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull, const void* _Nonnull)) __INTRODUCED_IN(21);
+void* _Nonnull lsearch(const void* _Nonnull __key, void* _Nonnull __array, size_t* _Nonnull __count, size_t __size, int (* _Nonnull __comparator)(const void* _Nonnull, const void* _Nonnull));
 
 /**
  * [tdelete(3)](http://man7.org/linux/man-pages/man3/tdelete.3.html) searches
@@ -214,6 +206,6 @@
  * [twalk(3)](http://man7.org/linux/man-pages/man3/twalk.3.html) calls
  * `__visitor` on every node in the tree.
  */
-void twalk(const void* _Nullable __root, void (* _Nullable __visitor)(const void* _Nullable, VISIT, int)) __INTRODUCED_IN(21);
+void twalk(const void* _Nullable __root, void (* _Nullable __visitor)(const void* _Nullable, VISIT, int));
 
 __END_DECLS