Return true if a useless computation was removed.

The case where the consequent and alternative are equal did not
set the bit correctly.

While this might lead to user-visible changes, such as more memory
being collected, it certainly is mainly observable when a live
visualization shows the control flow which is still alive (before
this change there were spurious disconnected <computation> nodes)
Cleanup references of an inlined computation

Previously there were some leftovers in the flow graph, but since
being disconnected not a big issue. It is observable in the
visualization, though. This change is most likely not observable
to an user.
Merge pull request #659 from hannesm/fixes

fixes of the flow graph during optimization
posix-threads.c: Include pthread_np.h on FreeBSD to get pthread_set_name_np prototype
unix-support: hide getebp behind ifdef OPEN_DYLAN_ARCH_X86 to get rid of the unused function warning
Merge pull request #661 from hannesm/runtime-freebsd-fixes

posix-threads.c: Include pthread_np.h on FreeBSD to get pthread_set_name...