[Win32] Overload ==, != for locale_t and long long

Summary:
_is_chartype_l (needed for isxdigit_l) in MinGW compares locale_t and NULL.
NULL is 'long long' for 64-bit, and this results in ambiguous overloads when
compiled with Clang.  Define a concrete overload for the operators to fix the
ambiguity.

Reviewers: mstorsjo, EricWF, srhines, danalbert

Subscribers: christof, cfe-commits, ldionne

Differential Revision: https://reviews.llvm.org/D48749

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@336141 91177308-0d34-0410-b5e6-96231b3b80d8

include/support/win32/locale_win32.h

@@ -46,6 +46,10 @@ public:
         return __left.__locale == nullptr && __right == 0;
     }
 
+    friend bool operator==(const locale_t& __left, long long __right) {
+        return __left.__locale == nullptr && __right == 0;
+    }
+
     friend bool operator==(const locale_t& __left, std::nullptr_t) {
         return __left.__locale == nullptr;
     }
@@ -66,6 +70,10 @@ public:
         return !(__left == __right);
     }
 
+    friend bool operator!=(const locale_t& __left, long long __right) {
+        return !(__left == __right);
+    }
+
     friend bool operator!=(const locale_t& __left, std::nullptr_t __right) {
         return !(__left == __right);
     }