devel/flang-clang: Update to a new snapshot and fix pkg-plist to match the recent upgrade of LLVM 5.0.0 to 5.0.1. Update requires patch to remove -ldl.

devel/flang: Bump PORTREVISION to force recompilation after the above companion compiler update.

PR: 225174 (for the LLVM 5.0.1)
Approved by: swills (mentor, implicit)