Wipe out references to defunct sourceforge

Wipe out references to defunct sourceforge

The old location of strace-devel mailing list is defunct, it used to
lose email messages and sometimes did not deliver any mails for days.

The mailing list has been moved to strace-devel@lists.strace.io.

* CREDITS.in: Update the mailing list address.
(Zhang Le): Update email address.
* README: Update the mailing list address.
* README.md: Likewise.
* configure.ac (AC_INIT): Likewise.
* strace.1.in (.SH REPORTING BUGS): Likewise.
* strace-log-merge.1.in (.SH REPORTING BUGS): Likewise.
* sched.c (SYS_FUNC(sched_getattr)): Update the mailing list reference.
* tests/scno_tampering.sh: Likewise.
* qemu_multiarch_testing/README: Update git repository address.
* NEWS: Mention the change of the mailing list address.

Closes: https://github.com/strace/strace/issues/38