[Bug target/85056] [nvptx] wrong declaration of external arrays

[cesar at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85056

--- Comment #1 from cesar at gcc dot gnu.org ---
Created attachment 43744
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43744&action=edit
WIP patch

It looks like nvptx_assmeble_decl_begin ignores the array type information.
This patch records whether it has detected an aggregate type on entry to that
function. Then it emits an empty '[]' if it has detected an aggregate type with
out a defined size.