Remove CloudABI specific workaround.

CloudABI has gained the mblen_l() function in the meantime that does
properly return whether the character set has shift-states (read:
never).


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@272886 91177308-0d34-0410-b5e6-96231b3b80d8

src/locale.cpp

@@ -1660,10 +1660,8 @@ codecvt<wchar_t, char, mbstate_t>::do_unshift(state_type& st,
 int
 codecvt<wchar_t, char, mbstate_t>::do_encoding() const  _NOEXCEPT
 {
-#ifndef __CloudABI__
     if (__libcpp_mbtowc_l(nullptr, nullptr, MB_LEN_MAX, __l) != 0)
         return -1;
-#endif
 
     // stateless encoding
     if (__l == 0 || __libcpp_mb_cur_max_l(__l) == 1)  // there are no known constant length encodings