isdigitrune() is not in libc.h or the manpage but it is in libc,
this patch fixes this situation by publishing it.

-Steve

Reference: /n/sources/patch/applied/isdigitrune
Date: Wed Mar  9 15:39:04 CET 2011
Signed-off-by: steve@quintile.net

--- /sys/include/libc.h	Wed Mar  9 15:27:20 2011
+++ /sys/include/libc.h	Wed Mar  9 15:27:01 2011
@@ -83,6 +83,7 @@
 extern	int	isspacerune(Rune);
 extern	int	istitlerune(Rune);
 extern	int	isupperrune(Rune);
+extern	int	isdigitrune(Rune);
 
 /*
  * malloc
--- /sys/man/2/isalpharune	Wed Mar  9 15:27:41 2011
+++ /sys/man/2/isalpharune	Wed Mar  9 15:27:29 2011
@@ -22,6 +22,9 @@
 int isupperrune(Rune c)
 .PP
 .B
+int isdigitrune(Rune c)
+.PP
+.B
 Rune tolowerrune(Rune c)
 .PP
 .B