Profiling every local kernel invocation should not be enabled without explicitly asking

[connorjward]

At present we add PETSc events to local kernels if PETSc logging is enabled (i.e. we pass -log_view).
In my recent performance experiments it is clear that this can actually be quite costly so enabling it by default like this is probably unwise. I think instead we should add a add_petsc_event parameter to tsfc_compiler_parameters so we have more control on when it is applied.