sysdeps: Ensure ieee128*_chk routines to be properly named

The *_chk routines naming doesn't match the name that would be generated
using libc_hidden_ldbl_proto. Since the macro is needed for some of
these *_chk functions for _FORTIFY_SOURCE to be enabled, that needed to
be fixed.
While at it, all the *_chk function get renamed appropriately for
consistency, even if not strictly necessary.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: Paul E. Murphy <murphyp@linux.ibm.com>