iconv.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
if_nametoindex.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
ilogb.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
index.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
isalpha.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
isatty.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
isgreater.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
iswalnum.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
iswalpha.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
iswblank.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
iswcntrl.3: Reformat thread-safety information

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
iswctype.3: Reformat thread-safety information

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