Rename uses of _ and __ because these are getting stepped on by macros from other system code.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@167038 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/memory b/include/memory
index fe5dd0c..4c12ad9 100644
--- a/include/memory
+++ b/include/memory
@@ -694,7 +694,7 @@
 struct __has_element_type
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::element_type* = 0);
 public:
@@ -782,7 +782,7 @@
 struct __has_difference_type
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::difference_type* = 0);
 public:
@@ -805,7 +805,7 @@
 struct __has_rebind
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Xp> static __two __test(...);
     template <class _Xp> static char __test(typename _Xp::template rebind<_Up>* = 0);
 public:
@@ -998,7 +998,7 @@
 struct __has_const_pointer
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::const_pointer* = 0);
 public:
@@ -1025,7 +1025,7 @@
 struct __has_void_pointer
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::void_pointer* = 0);
 public:
@@ -1052,7 +1052,7 @@
 struct __has_const_void_pointer
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::const_void_pointer* = 0);
 public:
@@ -1095,7 +1095,7 @@
 struct __has_size_type
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::size_type* = 0);
 public:
@@ -1118,7 +1118,7 @@
 struct __has_propagate_on_container_copy_assignment
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::propagate_on_container_copy_assignment* = 0);
 public:
@@ -1141,7 +1141,7 @@
 struct __has_propagate_on_container_move_assignment
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::propagate_on_container_move_assignment* = 0);
 public:
@@ -1164,7 +1164,7 @@
 struct __has_propagate_on_container_swap
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::propagate_on_container_swap* = 0);
 public:
@@ -1187,7 +1187,7 @@
 struct __has_rebind_other
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Xp> static __two __test(...);
     template <class _Xp> static char __test(typename _Xp::template rebind<_Up>::other* = 0);
 public:
@@ -5268,7 +5268,7 @@
 
 class __sp_mut
 {
-    void* _;
+    void* __lx;
 public:
     void lock() _NOEXCEPT;
     void unlock() _NOEXCEPT;
@@ -5395,17 +5395,17 @@
 //enum class
 struct _LIBCPP_VISIBLE pointer_safety
 {
-    enum _
+    enum __lx
     {
         relaxed,
         preferred,
         strict
     };
 
-    _ __v_;
+    __lx __v_;
 
     _LIBCPP_INLINE_VISIBILITY
-    pointer_safety(_ __v) : __v_(__v) {}
+    pointer_safety(__lx __v) : __v_(__v) {}
     _LIBCPP_INLINE_VISIBILITY
     operator int() const {return __v_;}
 };