Rename llvm::apply -> llvm::apply_tuple.

llvm::cl already has a function called llvm::apply() so this is
causing an ODR violation.  The STLExtras version should win the
vote on which one gets to be called apply() since it is named
after the equivalent STL function, but since renaiming the cl
version is more difficult, let's do this for now to get the
bots green.

llvm-svn: 283800