Order of libraries and source files in the f18 frontend

When the f18 frontend calls the link editor, put the libraries and object files in the correct order.

Fixes the issues reported here https://github.com/flang-compiler/flang/issues/897

Reviewed By: sscalpone, AlexisPerry

Differential Revision: https://reviews.llvm.org/D84340

(cherry picked from commit ca0bf440)