Add AGROUP from Linux 5.19 to sys/acct.h, remove Alpha version (bug 29502)

Add AGROUP from Linux 5.19 to sys/acct.h, remove Alpha version (bug 29502)

Linux 5.19 adds a new accounting flag AGROUP; add it to the
enumeration in sys/acct.h.

This shows up that the Alpha-specific variant of this header has a
different set of constants and struct acct, which appear to be the
constants and structure layout from Linux 2.0.  These were changed
some time between Linux 2.0 and Linux 2.2; I see no evidence of an
Alpha-specific layout or set of constants, but haven't checked the
detailed Linux kernel history between those versions.  Rather, it
looks like tha Alpha-specific header was originally needed because of
the use of types in the kernel structure (such as uid_t and gid_t)
that had different sizes on Alpha, and when glibc was updated for
changes to the structure and constants in the kernel

1998-10-02  Andreas Jaeger  <aj@arthur.rhein-neckar.de>

        * sysdeps/unix/sysv/linux/sys/acct.h: Bring in sync with current
        linux 2.1 version.

that simply omitted to do anything about the Alpha version.

Thus, remove the Alpha version in order to get the updated definitions
into use on Alpha, as I don't think the interfaces are actually
different for Alpha with any kernel version supported by glibc.

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