[IR] Accept 'const Type &' in the Type operator<<. NFC.
[IR] Accept 'const Type &' in the Type operator<<. NFC.

Type::print is const; there's no reason for the operator not to be.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@295227 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 4e2172c3297e2edd5cdb8104bdfc903fb7b996d4)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm