Enable jemalloc by default on non windows targets

[jimmygchen]

Issue Addressed

A few discord users that build Lighthouse from source has reported high RAM usage since v5.2.0. @michaelsproul and @chong-he have found that this is due to jemalloc feature being disabled. This is now necessary (on linux) with the introduction of tree-states and should always be enabled.

The Dockerfile doesn't have a default for FEATURES:

lighthouse/Dockerfile

Lines 4 to 7 in f1d88ba

	ARG FEATURES
	ARG PROFILE=release
	ARG CARGO_USE_GIT_CLI=true
	ENV FEATURES $FEATURES

From @michaelsproul

it sets it as an argument, which I think means if you don't do --arg FEATURES=jemalloc it will build with FEATURES=""

This PR removes the feature flag and enables jemalloc by default on non windows targets, even when it's not specified via FEATURES environment variable.

[jimmygchen]

Oops looks like this doesn't work in windows, I'll look into it.

[michaelsproul]

With the jemalloc feature deprecated, we should update the allocator_name() function used to show the allocator in lighthouse --version to use the same logic (display "system" on Windows and "jemalloc" on everything else):

lighthouse/lighthouse/src/main.rs

Lines 53 to 59 in f1d88ba

	fn allocator_name() -> &'static str {
	if cfg!(feature = "jemalloc") {
	"jemalloc"
	} else {
	"system"
	}
	}

[jimmygchen]

Nice catch, updated!

[michaelsproul]

@Mergifyio queue

[mergify]

queue

✅ The pull request has been merged automatically

The pull request has been merged automatically at a910a49