Undefined symbols: _I_

[Marius Schamschula <mschamschula gmail com>]

While building gtk+ 2.8.6 under Mac OS X 10.3.9/Darwin 7.9.0, using
gcc 3.3 I ran into the following:

/bin/sh ../libtool --mode=link gcc  -O3 -funroll-loops
-fstrict-aliasing -Wall   -o testcalendar  testcalendar.o
../gdk-pixbuf/libgdk_pixbuf-2.0.la ../gdk/libgdk-x11-2.0.la
../gtk/libgtk-x11-2.0.la
gcc -O3 -funroll-loops -fstrict-aliasing -Wall -o .libs/testcalendar
testcalendar.o  ../gdk-pixbuf/.libs/libgdk_pixbuf-2.0.dylib
-L/usr/local/lib ../gdk/.libs/libgdk-x11-2.0.dylib -L/usr/X11R6/lib
../gtk/.libs/libgtk-x11-2.0.dylib
/tmp/gtk+2-2.8.6/gdk/.libs/libgdk-x11-2.0.dylib -lXrandr -lXinerama
-lXext -lXcursor
/tmp/gtk+2-2.8.6/gdk-pixbuf/.libs/libgdk_pixbuf-2.0.dylib
/usr/local/lib/libpangocairo-1.0.dylib
/usr/local/lib/libpangoft2-1.0.dylib /usr/local/lib/libpango-1.0.dylib
/usr/local/lib/libatk-1.0.dylib /usr/local/lib/libgobject-2.0.dylib
/usr/local/lib/libgmodule-2.0.dylib /usr/local/lib/libglib-2.0.dylib
/usr/lib/libiconv.dylib /usr/local/lib/libintl.dylib
/usr/local/lib/libiconv.dylib /usr/local/lib/libcairo.dylib
/usr/local/lib/libXrender.dylib -lX11
/usr/local/lib/libfontconfig.dylib /usr/local/lib/libexpat.dylib
/usr/local/lib/libfreetype.dylib /usr/local/lib/libtiff.dylib -lc
/usr/local/lib/libjpeg.dylib -lpng12 -lz -lm
ld: Undefined symbols:
_I_
make[2]: *** [testcalendar] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Where does the symbol _I_ come from?

I found nothing in Google. Any ideas?

TIA
--
Marius