[llvm-exegesis] Rename InstructionInstance into InstructionBuilder.

Summary: Non functional change.

Subscribers: tschuett, courbet, llvm-commits

Differential Revision: https://reviews.llvm.org/D50176

llvm-svn: 338701
GitOrigin-RevId: 171f3f46c869c0ec898bf4c2a33d10707fc03a9f
10 files changed