Fix `hygienic-scope`s in inner macro expansions (#58965)
Changes from https://github.com/JuliaLang/julia/pull/43151, github just
didn't want me to re-open it.
As discussed on slack, any `hygienic-scope` within an outer
`hygienic-scope` can read and write variables in the outer one, so it's
not particularly hygienic. The result is that we can't safely nest macro
calls unless they know the contents of all inner macro calls.
Should fix #48910.
Co-authored-by: Michiel Dral <m.c.dral@gmail.com>
(cherry picked from commit ff33305061cf5ea910631c4ab83a455f47eed774)