Update header versions for NDK platform fixes.

Bug: http://b/28178111
Change-Id: Icd638673b409aa43a91490f77c6b4d79c9ea20d9
diff --git a/libc/include/pwd.h b/libc/include/pwd.h
index b45780e..e881129 100644
--- a/libc/include/pwd.h
+++ b/libc/include/pwd.h
@@ -122,8 +122,8 @@
 void setpwent(void) __INTRODUCED_IN_FUTURE;
 void endpwent(void) __INTRODUCED_IN_FUTURE;
 
-int getpwnam_r(const char*, struct passwd*, char*, size_t, struct passwd**) __INTRODUCED_IN(21);
-int getpwuid_r(uid_t, struct passwd*, char*, size_t, struct passwd**) __INTRODUCED_IN(21);
+int getpwnam_r(const char*, struct passwd*, char*, size_t, struct passwd**) __INTRODUCED_IN(12);
+int getpwuid_r(uid_t, struct passwd*, char*, size_t, struct passwd**) __INTRODUCED_IN(12);
 
 __END_DECLS