pldd.1, bpf.2, clone.2, dup.2, ioctl_fat.2, nfsservctl.2, open_by_handle_at.2, perf_e...

pldd.1, bpf.2, clone.2, dup.2, ioctl_fat.2, nfsservctl.2, open_by_handle_at.2, perf_event_open.2, pivot_root.2, request_key.2, sched_setaffinity.2, seccomp.2, select.2, statx.2, dl_iterate_phdr.3, dlinfo.3, dlopen.3, insque.3, newlocale.3, printf.3, pthread_setname_np.3, rpc.3, stdarg.3, strfmon.3, veth.4, proc.5, slabinfo.5, cgroup_namespaces.7, cgroups.7, cpuset.7, fanotify.7, inotify.7, mount_namespaces.7, sock_diag.7, user_namespaces.7, ld.so.8: Use \(aq instead of ' inside monospace fonts

Use \(aq to get an unslanted single quote inside monospace code
blocks. Using a simple ' results in a slanted quote inside PDFs.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>