brk.2, chroot.2, clock_nanosleep.2, getpagesize.2, posix_fadvise.2, select.2, select_...

brk.2, chroot.2, clock_nanosleep.2, getpagesize.2, posix_fadvise.2, select.2, select_tut.2, seteuid.2, clock_getcpuclockid.3, ecvt.3, exp2.3, fseeko.3, gcvt.3, getdtablesize.3, getpass.3, getw.3, log2.3, mktemp.3, mq_receive.3, mq_send.3, posix_fallocate.3, posix_madvise.3, posix_memalign.3, pthread_attr_setstack.3, rint.3, sem_wait.3, setenv.3, sockatmark.3, strerror.3: Simplify FTM requirements

Looking at <features.h> (or feature_test_macros(7)), one can
see that when _XOPEN_SOURCE is defined with the value 600
(or greater), then _POSIX_C_SOURCE is defined with the value
200112L (or greater). Therefore, terms in the man pages such as

    _XOPEN_SOURCE\ >=\ 600 || _POSIX_C_SOURCE\ >=\ 200112L

can be simpified to:

    _POSIX_C_SOURCE\ >=\ 200112L

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