TCE: do not use the compiled simulator as it seems to have
dynamic library loading problems. The loaded engines do not
find TCE's symbols even though libpocl.so has libtce.so link.

The dlopen chain (icd->pocl->libtce->engine) probably hides the
libtce symbols at some point. It might be fixed by recording
the libtce.so to the engine .so, but it's not trivial.
Forgot this one too.