libc++: support newlib's ctype

Summary: Newlib supports ctype differently from other platforms, this patch teaches libc++ about yet another platform that does ctype differently.

Reviewers: jroelofs

Subscribers: cfe-commits, danalbert, EricWF, jvoung, jfb, mclow.lists

Differential Revision: http://reviews.llvm.org/D7888

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@230557 91177308-0d34-0410-b5e6-96231b3b80d8

src/locale.cpp

@@ -1033,6 +1033,9 @@ ctype<char>::classic_table()  _NOEXCEPT
 // going to end up dereferencing it later...
 #elif defined(__EMSCRIPTEN__)
     return *__ctype_b_loc();
+#elif defined(_NEWLIB_VERSION)
+    // Newlib has a 257-entry table in ctype_.c, where (char)0 starts at [1].
+    return _ctype_ + 1;
 #elif defined(_AIX)
     return (const unsigned int *)__lc_ctype_ptr->obj->mask;
 #elif defined(__ANDROID__)