profiling: improve 3.12 error message for calling lsprof twice
Python 3.12 prevent lsprof to be enabled if it is already enabled. This break
the use of lsprof in `hg serve` as both the initial `serve` command and the
request serving want to profile.
The "stat" profiler (the default) does not have this problem, so we focus on
improving the error message for now.
# name space package to host third party extensions
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)