control: Delete a parameter when nullopt is used

This commit changes the Manager::setParameter function to take a
std::optional.  When std::nullopt is passed in, the parameter is
deleted.  This removes the need for a separate deleteParameter function
and simplifies a code path that uses it.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: Ia32bc0e977245bd7d06b8d12c0cdfd79b981e4ba
2 files changed