Revert "Update aosp/master libcxx rebase to r263688"

The world is burning.

This reverts commit c004fd909c006eec55077c52ee119e1fa338c9e9, reversing
changes made to 1418e4163da4bb0b9e3fe496e51c23a0dce399d9.
diff --git a/include/__split_buffer b/include/__split_buffer
index 79d1aa1..727b1b6 100644
--- a/include/__split_buffer
+++ b/include/__split_buffer
@@ -56,12 +56,9 @@
     _LIBCPP_INLINE_VISIBILITY pointer&              __end_cap() _NOEXCEPT       {return __end_cap_.first();}
     _LIBCPP_INLINE_VISIBILITY const pointer&        __end_cap() const _NOEXCEPT {return __end_cap_.first();}
 
-    _LIBCPP_INLINE_VISIBILITY
     __split_buffer()
         _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
-    _LIBCPP_INLINE_VISIBILITY
     explicit __split_buffer(__alloc_rr& __a);
-    _LIBCPP_INLINE_VISIBILITY
     explicit __split_buffer(const __alloc_rr& __a);
     __split_buffer(size_type __cap, size_type __start, __alloc_rr& __a);
     ~__split_buffer();
@@ -131,9 +128,7 @@
 
     _LIBCPP_INLINE_VISIBILITY void __destruct_at_begin(pointer __new_begin)
         {__destruct_at_begin(__new_begin, is_trivially_destructible<value_type>());}
-        _LIBCPP_INLINE_VISIBILITY
         void __destruct_at_begin(pointer __new_begin, false_type);
-        _LIBCPP_INLINE_VISIBILITY
         void __destruct_at_begin(pointer __new_begin, true_type);
 
     _LIBCPP_INLINE_VISIBILITY
@@ -271,7 +266,7 @@
 }
 
 template <class _Tp, class _Allocator>
-inline
+inline _LIBCPP_INLINE_VISIBILITY
 void
 __split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, false_type)
 {
@@ -280,7 +275,7 @@
 }
 
 template <class _Tp, class _Allocator>
-inline
+inline _LIBCPP_INLINE_VISIBILITY
 void
 __split_buffer<_Tp, _Allocator>::__destruct_at_begin(pointer __new_begin, true_type)
 {
@@ -314,7 +309,7 @@
 }
 
 template <class _Tp, class _Allocator>
-inline
+inline _LIBCPP_INLINE_VISIBILITY
 __split_buffer<_Tp, _Allocator>::__split_buffer()
     _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
     : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr)
@@ -322,14 +317,14 @@
 }
 
 template <class _Tp, class _Allocator>
-inline
+inline _LIBCPP_INLINE_VISIBILITY
 __split_buffer<_Tp, _Allocator>::__split_buffer(__alloc_rr& __a)
     : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
 {
 }
 
 template <class _Tp, class _Allocator>
-inline
+inline _LIBCPP_INLINE_VISIBILITY
 __split_buffer<_Tp, _Allocator>::__split_buffer(const __alloc_rr& __a)
     : __first_(nullptr), __begin_(nullptr), __end_(nullptr), __end_cap_(nullptr, __a)
 {