[ODE] GIMPACT and dMassSetTrimesh Compatibility

[David Walters]

I've applied patch # 1587462 to SVN revision #1114. This fixes the
mass problem in test_moving_trimesh in GIMPACT mode.

Francisco, in future, please can you submit .diff patches instead of
replacement files as they are _much_ easier to see what has changed
and will be much more likely to be looked at and evaluated properly.

Plus it provides future proofing to files that may change several
times before a patch is integrated - there is a severe danger here of
getting merge errors and losing valuable contributions.

Thanks,
David