Features from optional dependencies

jemalloc-ctl implicit feature

Enables jemalloc-ctl ^0.3.3

jemalloc-ctl:

A safe wrapper over jemalloc's control and introspection APIs

Affects instruments::jemalloc

log implicit feature

Enables log

log:

A lightweight logging facade for Rust

Affects util::log_error, util::log_warning, util::log_info