remove inalloca parameters in globalopt and simplify argpromotion

Summary:
Inalloca parameters require special handling in some optimizations.
This change causes globalopt to strip the inalloca attribute from
function parameters when it is safe to do so, removes the special
handling for inallocas from argpromotion, and replaces it with a
simple check that causes argpromotion to skip functions that receive
inallocas (for when the pass is invoked on code that didn't run
through globalopt first). This also avoids a case where argpromotion
would incorrectly try to pass an inalloca in a register.

Fixes PR41658.

Reviewers: rnk, efriedma

Reviewed By: rnk

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61286

llvm-svn: 359743