libc: Match header annotations to version script

According to `libc.map.txt`, `pselect64()` was introduced since API
level 28. This commit adds the annotations to `sys/select.h`.

Bug: 113263746
Test: ./bionic/tools/versioner/run_tests.py
Change-Id: I70ea4b23cef92857f1654cebb660e0219238fc95
diff --git a/libc/include/sys/select.h b/libc/include/sys/select.h
index e58df21..9be444c 100644
--- a/libc/include/sys/select.h
+++ b/libc/include/sys/select.h
@@ -80,7 +80,7 @@
 
 int select(int __fd_count, fd_set* __read_fds, fd_set* __write_fds, fd_set* __exception_fds, struct timeval* __timeout);
 int pselect(int __fd_count, fd_set* __read_fds, fd_set* __write_fds, fd_set* __exception_fds, const struct timespec* __timeout, const sigset_t* __mask);
-int pselect64(int __fd_count, fd_set* __read_fds, fd_set* __write_fds, fd_set* __exception_fds, const struct timespec* __timeout, const sigset64_t* __mask);
+int pselect64(int __fd_count, fd_set* __read_fds, fd_set* __write_fds, fd_set* __exception_fds, const struct timespec* __timeout, const sigset64_t* __mask) __INTRODUCED_IN(28);
 
 __END_DECLS