[ExecutionEngine] Add JITSymbolFlags::fromSummary(GlobalValueSummary*)

Summary: A function that creates JITSymbolFlags from a GlobalValueSummary. Similar functions exist: fromGlobalValue(), fromObjectSymbol()

Reviewers: lhames

Reviewed By: lhames

Subscribers: hiraditya, steven_wu, dexonsmith, arphaman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75082