#945 marco preppatch.tcl crash on linux

[Philippe C]

On linux ubuntu dapper when i use gcvs and the menu
"macro/prepare patch from [pwd]" I get the following
message in the gcvs window :

Loaded settings for /home/philippe/cvs/torque/engine
successfully...
Welcome to gcvs 1.0
CVSROOT: x......x@cvs.garagegames.com (password
authentication)
TCL is available, shell and macros are enabled : help
(select and press enter)
Iterating directories...
Diff'ing new files locally...
couldn't execute "c:/cygwin/bin/diff.exe": no such file
or directory

I have fixed the issues like that on my linux version
in the file usr/share/gcvs/PrepPatch.tcl :

#set ourDiffApp "c:/cygwin/bin/diff.exe"
set ourDiffApp "diff"

With this patch the macro works and i get the patch.