librustc: Make addresses of immutable statics insignificant unless
`#[inline(never)]` is used.

Closes #8958.

This can break some code that relied on the addresses of statics
being distinct; add `#[inline(never)]` to the affected statics.

[breaking-change]
auto merge of #14977 : pcwalton/rust/address-insignificant-reform, r=brson

`#[inline(never)]` is used.

Closes #8958.

This can break some code that relied on the addresses of statics
being distinct; add `#[inline(never)]` to the affected statics.

[breaking-change]

r? @brson