BitcodeWriter: WorkList => Worklist, NFC
BitcodeWriter: WorkList => Worklist, NFC

I have no idea how I chose two different spellings in the space of a
couple of weeks, but now I can't remember what to use where.  Choose
"Worklist".

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@266582 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 35f771e8a97616c3f7234d5c12114b1129b78ee8)

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