Merge commit 00925aadb from llvm git (by Fangrui Song):

[ELF][PPC32] Fix canonical PLTs when the order does not match the PLT order

Reviewed By: Bdragon28

Differential Revision: https://reviews.llvm.org/D75394

This is needed to fix miscompiled canonical PLTs on ppc32/lld10.

Requested by: bdragon
MFC after: 6 weeks
X-MFC-With: 358851
Differential Revision: https://reviews.freebsd.org/D24109