Fix typo "fuction" noticed in comments in AssumptionCache.h, and also all the other...

Fix typo "fuction" noticed in comments in AssumptionCache.h, and also all the other files that have the same typo. All comments, no functionality change! (Merely a "fuctionality" change.)

Bonus change to remove emacs major mode marker from SystemZMachineFunctionInfo.cpp because emacs already knows it's C++ from the extension. Also fix typo "appeary" in AMDGPUMCAsmInfo.h.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243585 91177308-0d34-0410-b5e6-96231b3b80d8