add_key.2, bpf.2, fcntl.2, futex.2, listxattr.2, perf_event_open.2, prctl.2, request_...

add_key.2, bpf.2, fcntl.2, futex.2, listxattr.2, perf_event_open.2, prctl.2, request_key.2, sigaltstack.2, __ppc_set_ppr_med.3, __ppc_yield.3, getw.3, setbuf.3, setjmp.3, lirc.4, core.5, securetty.5, inode.7, keyrings.7, process-keyring.7, user-keyring.7, ld.so.8: srcfix: use .PP instead of .P

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