[PatternMatch] Add support for matching intrinsics with 5 operands.

Summary: Also adds a test to the pattern matching unit tests.

Reviewers: spatel, craig.topper, RKSimon, majnemer, lebedev.ri

Reviewed By: spatel

Subscribers: merge_guards_bot, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70892