Rebase: [cherry-pick] [BOLT] Add option to skip writing an output file

Summary:
The user may wish to run BOLT for printing statistics only
(i.e. to check that the profile is valid). Add an option to run BOLT
without writing any output file, similar to a dry run. This option
is triggered by supplying -o with "/dev/null".

(cherry picked from FBD29568632)