profile: support --profile in alias and abbreviated version (--prof)
We now process the "--profile" a second time after alias has been processed and
the command argument fully parsed. If appropriate we enable profiling at that
time.
In these situation, the --profile will cover less than if the full --profile
flag was passed on the command line. This is better than the previous behavior
(flag ignored) and still fullfil multiple valid usecases.
#
# Avoid interference from actual test env:
unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL