Patch by Daniel Lupei, fixing a performance bug with the
counterexample cache.  (This is an old patch, reported at
http://llvm.org/bugs/show_bug.cgi?id=11435, on KLEE's old bug tracking
system.)
Merge pull request #76 from srg-imperial/master

Patch by Daniel Lupei, fixing a performance bug with the counterexample cache.  (This is an old patch, reported at http://llvm.org/bugs/show_bug.cgi?id=11435, on KLEE's old bug tracking system.)