rts: Disable -hb with multiple capabilities

Authored by bgamari on Sep 12 2016, 7:44 AM.

Description

rts: Disable -hb with multiple capabilities

Biographical profiling is not thread-safe as documented in Trac #12019. Throw
an error when it is used in this way.

Test Plan: Validate

Reviewers: simonmar, austin, erikd

Reviewed By: erikd

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2516

GHC Trac Issues: Trac #12019