missing function prototype for split_into_lines

[Wolfgang Sourdeau <wolfgang ultim net>]

This bug has appeared in gnome-libs-0.60 and is still present in 0.61.
It affects libgnomeui/gnome-canvas-text.c where this function is
declared after calls to it.
I am using gcc 2.95.2 and it stops the compilation process. Declaring
the correct prototype at the top of the file fix the problem. 


Wolfgang