We've been relying on frame pointers being indirectly enabled via things
like --enable-profiling for some time, but this doesn't scale because
some things may want frame pointers while wanting --disable-profiling.

So we move MOZ_FRAMEPTR_FLAGS to python configure and add a new option
to decide whether to enable frame pointers or not.

Differential Revision: https://phabricator.services.mozilla.com/D34117

--HG--
extra : moz-landing-system : lando