isalpha.3: ATTRIBUTES: Note functions that are thread-safe

The functions isalnum(), isalpha(), isascii(), isblank(),
iscntrl(), isdigit(), isgraph(), islower(), isprint(),
ispunct(), isspace(), isupper() and isxdigit() are thread safe.

Signed-off-by: Peng Haitao <penght@cn.fujitsu.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man3/isalpha.3

@@ -27,7 +27,7 @@
 .\" Modified Sat Sep  2 21:52:01 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
 .\" Modified Mon May 27 22:55:26 1996 by Martin Schulze (joey@linux.de)
 .\"
-.TH ISALPHA 3 2010-09-20 "GNU" "Linux Programmer's Manual"
+.TH ISALPHA 3 2014-01-27 "GNU" "Linux Programmer's Manual"
 .SH NAME
 isalnum, isalpha, isascii, isblank, iscntrl, isdigit, isgraph, islower,
 isprint, ispunct, isspace, isupper, isxdigit \- character
@@ -162,6 +162,24 @@ The values returned are nonzero if the character
 .I c
 falls into the tested class, and a zero value
 if not.
+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+The
+.BR isalnum (),
+.BR isalpha (),
+.BR isascii (),
+.BR isblank (),
+.BR iscntrl (),
+.BR isdigit (),
+.BR isgraph (),
+.BR islower (),
+.BR isprint (),
+.BR ispunct (),
+.BR isspace (),
+.BR isupper (),
+and
+.BR isxdigit ()
+functions are thread-safe.
 .SH CONFORMING TO
 C99, 4.3BSD.
 C89 specifies all of these functions except