Cannot find iswctype (code in libc!) using i386-Linux

["Rob O'Connell" <oconnell aida physics wisc edu>]

Hi All - 
in a nutshell my error is:
.libs/libgtk.so: undefined reference to `iswctype'

whilst making the library.  
iswctyoe is from libc and in the code that breaks if I add /lib/libc.so.5
to it, it compiles...but I don't know "configure" very well, and so
I haven't been able to fix this. (whoops should be iswctype at start of
this sentence!)

I'm trying gtk version 0.99.3, my libc version is:libc.so.5.4.38

I've searched the archives and can't find this problem...but I'm running
a fairly standard linux (Redhat 4.1 if I remember correctly...but some
libs may have changed...but nothing too funky!)

Any help would be greatly appreciated!
Thanks
Rob O'Connell.