Move the InsertPrologEpilogCode class out of the Sparc.cpp file into the

Move the InsertPrologEpilogCode class out of the Sparc.cpp file into the
new PrologEpilogCodeInserter.cpp file, and include the bodies of the
GetInstructionsFor(Prolog|Epilog) functions from SparcInstrSelection.cpp
into the class.  This eliminates the need for a static global vector of
instructions and a class of errors that is really unneccesary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2194 91177308-0d34-0410-b5e6-96231b3b80d8