Newbie--Problem installing GTK

["Lucian P. Smith" <lpsmith bioc rice edu>]

Hello!  Sorry to disturb you all, but I figured you'd be the ones who'd
know.  I'm trying to install GTK on an SGI Indy running IRIX 5.1 into my
home directory (don't worry, there's plenty of space) so that I can then
install GIMP.  Everything seems to run smoothly after running the configure 
file:

./configure --prefix=/home/heme/d1/lpsmith/gimp/

but then when running 'make', I get (after a bunch of stuff):

Making install in gdk
        /bin/sh ../libtool --mode=compile gcc -DHAVE_CONFIG_H -I. -I. -I..
-I.. -I../glib    -O2 -DNDEBUG -DUSE_XIM -c gdk.c
gcc -DHAVE_CONFIG_H -I. -I. -I.. -I.. -I../glib -O2 -DNDEBUG -DUSE_XIM -c
-DPIC gdk.c
In file included from gdk.h:22,
                 from gdk.c:45:
../gdk/gdktypes.h:22: wchar.h: No such file or directory
In file included from gdk.h:23,
                 from gdk.c:45:
../gdk/gdki18n.h:25: wchar.h: No such file or directory
*** Error code 1 (bu21)
*** Error code 1 (bu21)

Can anyone tell me what the hangup here is?  Thanks!

-Lucian Smith