We always call correctOptions() before recomputeDependentOptions(), and often call dumpOptionsIfNeeded() and ensureOptionsAreCoherent() after.

This patch makes things more consistent by:
1. Rename recomputeDependentOptions() to notifyOptionsChanged().
2. Rename ensureOptionsAreCoherent() to assertOptionsAreCoherent(), because "ensure" implies that the function will make them coherent.  Instead, the function asserts that they are coherent.
3. Move the body of correctOptions() (which is a tiny function) into the top of notifyOptionsChanged().
4. Call dumpOptionsIfNeeded() and assertOptionsAreCoherent() at the end of notifyOptionsChanged() instead of from clients.
5. Make sure clients call notifyOptionsChanged() after changing options.

Additionally:
6. Rename ExecutableAllocator:: setJITEnabled() to ExecutableAllocator::disableJIT().  Disabling JIT in this function was always a one way street, and there's no going back.  This rename makes it clear and explicit.