message: [jemallocator] turn off alloc_trait feature
  Turn off the `alloc_trait` feature of the jemallocator crate since we
  aren't actively using the feature and it requires the use the of nightly
  feature `allocator_api`.
  Closes:
  Approved by: metajack
diff: @@ -9,7 +9,7 @@ edition = "2018"
  [dependencies]
  grpcio = { version = "0.4.4", default-features = false, features = ["protobuf-codec"] }
  grpcio-sys = "0.4.4"
  -jemallocator = { version = "0.3.2", features = ["alloc_trait", "profiling", "unprefixed_malloc_on_supported_platforms"] }
  +jemallocator = { version = "0.3.2", features = ["profiling", "unprefixed_malloc_on_supported_platforms"] }
  parity-multiaddr = "0.5.0"
  rayon = "1.2.0"
  signal-hook = "0.1.10"
  