inheriting C symbols

The package coxme depends heavily on bdsmatrix, to the point of needing
access to some of its C calls.  The kinship package (in progress) uses
the R level functions in bdsmatrix, but not the C calls.  That is, I
don't want to always export the symbols.

For testing I can use an explicit dyn.load('somepath/bsdmatrix.so',
local=F).  How do I incorporate such a dependency in the DESCRIPTION
file for coxme, so that it happens in general?

Terry T.