Setup heap profiling support

[howardjohn]

And make sure existing CPU profiling still works

[stevenctl]

Is this working? I see there's a gprof/heap endpoint now

[howardjohn]

Basically you can swap out heap allocators, and each one has their own profiling methods. gprof in particular was very hard to compile. I think it could be statically linked but I couldn't figure out how. And may have implications beyond profiling

[hzxuzhonghu]

/assign

[hzxuzhonghu]

gperftools https://github.com/dignifiedquire/rust-gperftools has not been active for 4 years. Do we still want to use it?

[howardjohn]

Aside from 4 years old it also doesn't statically link so I think its probably problematic

[howardjohn]

tracking more in #863