[ODE] minor issues with ode 0.7

[Goneri Le Bouder]

>> * fix_dTRIMESH_ENABLED_undef.diff:
>> if ./configure is called with --disable-opcode, heightfield.cpp failed
>> to build.
>
> I'm submitted a fix for this, thanks for drawing it to my attention!
Thank you.

> ps. I've not looked at the other issue regarding the 'DESTDIR'
> variable, so that is still an open problem.
Can you please have a look on this little patch?

Regards,


       Gonéri