Change name of copyFlags() to copyIRFlags(). Add convenience method for logical 'and' of all flags. NFC.

Adding 'IR' to the names in an attempt to be less ambiguous about the flags we're dealing with here.

The 'and' method is needed by the SLPVectorizer (PR20802) and possibly other passes.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217004 91177308-0d34-0410-b5e6-96231b3b80d8