"Uniform prefixing" across platforms

I'm in a situation where I would like to use jemalloc as an "alternate"/"additional" allocator, while not overriding the system allocator. Given the package in its current state, that's hard, because on macOS, `malloc` will not be overridden, while on Linux, it will. Would you be open to adding an additional (conda) output to this package that has the `je_` prefix across all platforms? If so, I'd be happy to try my hand at it in a PR.

cc @matthiasdiener @lukeolson

Start by reviewing the feedstock's package recipe and its platform-specific build settings. Confirm how outputs are declared and how jemalloc symbols are configured on macOS and Linux; done means an additional conda output provides the je_ prefix consistently without overriding the system allocator.

Written by the indexing model from the issue text.