...the code had been like this ever since it got introduced with
6d492447 "118160: Use CoinMP as replacement for
lp_solve," but it looks more plausible that the return values should be checked
rather than be ignored.  At least, CppunitTest_sccomp_lpsolver keeps succeeding
after the change (with --enable-coinmp).

Change-Id: If450827ae034079c9ee69b4e49c55b480ac0de06