[IRSim][IROutliner] Ignoring Musttail Function

Musttail calls require extra handling to properly propagate the calling convention information and tail call information. The outliner does not currently do this, so we ignore call instructions that utilize the swifttailcc and tailcc calling convention as well as functions marked with the attribute musttail.

Reviewers: paquette, aschwaighofer

Differential Revision: https://reviews.llvm.org/D120733