Brought call_once variadic call up to current spec, which allows move-only functors and move-only arguments, but disallows functors with non-const lvalue reference parameters.

llvm-svn: 131414

llvm-svn: 123337

llvm-svn: 119909

llvm-svn: 119395

llvm-svn: 114559

Changed __config to react to all of clang's currently documented has_feature flags, and renamed _LIBCPP_MOVE to _LIBCPP_HAS_NO_RVALUE_REFERENCES to be more consistent with the rest of the libc++'s flags, and with clang's nomenclature.

llvm-svn: 113086

llvm-svn: 111750

llvm-svn: 103516

llvm-svn: 103490