[ELF] Handle GCC collect2 -plugin-opt= on Windows

Follows up on commit cd5d5ce2 by
additionally ignoring relative paths ending in "lto-wrapper.exe" as
can be the case for GCC cross-compiled for Windows.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D138065

(cherry picked from commit cf4f35b7)