Add PTRACE_GET_RSEQ_CONFIGURATION from Linux 5.13 to sys/ptrace.h

Linux 5.13 adds a PTRACE_GET_RSEQ_CONFIGURATION constant, with an
associated ptrace_rseq_configuration structure.

Add this constant to the various sys/ptrace.h headers in glibc, with
the structure in bits/ptrace-shared.h (named struct
__ptrace_rseq_configuration in glibc, as with other such structures).

Tested for x86_64, and with build-many-glibcs.py.