Rollup merge of #61077 - nnethercote:tweak-prefill, r=petrochenkov
Rollup merge of #61077 - nnethercote:tweak-prefill, r=petrochenkov

Don't arena-allocate static symbols.

It's just a waste of memory. This also gets rid of the special case for
"".

r? @petrochenkov

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust