<unistd.h> __INTRODUCED_IN cleaup.

The NDK doesn't support anything older than API level 16, so remove some
more clutter.

Test: builds
Change-Id: If257a27841396af001b089b7ae0fbd8c3e0128e4
diff --git a/libc/include/bits/fortify/unistd.h b/libc/include/bits/fortify/unistd.h
index 547a168..c42bd0c 100644
--- a/libc/include/bits/fortify/unistd.h
+++ b/libc/include/bits/fortify/unistd.h
@@ -35,14 +35,13 @@
 ssize_t __pread_real(int, void*, size_t, off_t) __RENAME(pread);
 
 ssize_t __pread64_chk(int, void*, size_t, off64_t, size_t) __INTRODUCED_IN(23);
-ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64) __INTRODUCED_IN(12);
+ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64);
 
 ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t) __INTRODUCED_IN(24);
 ssize_t __pwrite_real(int, const void*, size_t, off_t) __RENAME(pwrite);
 
 ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t) __INTRODUCED_IN(24);
-ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64)
-  __INTRODUCED_IN(12);
+ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64);
 
 ssize_t __read_chk(int, void*, size_t, size_t) __INTRODUCED_IN(21);
 ssize_t __write_chk(int, const void*, size_t, size_t) __INTRODUCED_IN(24);