Modifications to get nib2gmodel building with new make

[Pete French]

Been playing around with this all evening, and got it to go (I dont
normally have much to do with gmake so it took a long time for a short answer).

To make nib2gmodel build you need to:

1) Remove "rootinstall.sh" and "rootuninstall.sh" from the dependencies
   in nib2gmodel/GNUmakefile.in

2) Re-add the line "ADDITIONAL_TOOL_LIBS += -lgmodel" into the file
   nib2gmodel/gui/Model/GNUmakefile

Could someone verify these please and put them into CVS ? I am a bit
uneasy about the second change as I cant see how the line would have been
removed without a good reason.

This compiled fine for me on m68k hardware, I havent checked it yet on
an Intel system. the resulting gmodel files from the m68k run fine under
the latest GNUstep on i386 though.

-bat.