[X86][MC]: Adding test coverage of MC encoding for several small extensions.<NFC>

NFC.
 Adding MC regressions tests to cover several small x86 extensions as follows:
 CLWB, CLZERO, F16C, INVPCID, PKU, POPCNT, RTM, SGX, SHA, SVM, VMFUNC, VTX

This patch is part of a larger task to cover MC encoding of all X86 isa sets started in revision: https://reviews.llvm.org/D39952

Reviewers: RKSimon, craig.topper, zvi, AndreiGrischenko
Differential Revision: https://reviews.llvm.org/D41388

Change-Id: I254508cd17faca00b780be0fc2abf6c71b61faab
llvm-svn: 324595