Add markup for libc++ dylib availability

Libc++ is used as a system library on macOS and iOS (amongst others). In order
for users to be able to compile a binary that is intended to be deployed to an
older version of the platform, clang provides the
availability attribute <https://clang.llvm.org/docs/AttributeReference.html#availability>_
that can be placed on declarations to describe the lifecycle of a symbol in the
library.

See docs/DesignDocs/AvailabilityMarkup.rst for more information.

Differential Revision: https://reviews.llvm.org/D31739

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@302172 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/new b/include/new
index c0e7b2d..34df2ef 100644
--- a/include/new
+++ b/include/new
@@ -146,9 +146,8 @@
 
 #if defined(_LIBCPP_BUILDING_LIBRARY) || (_LIBCPP_STD_VER > 11)
 
-class _LIBCPP_EXCEPTION_ABI bad_array_length
-    : public bad_alloc
-{
+class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_ARRAY_LENGTH
+    bad_array_length : public bad_alloc {
 public:
     bad_array_length() _NOEXCEPT;
     virtual ~bad_array_length() _NOEXCEPT;
@@ -182,7 +181,7 @@
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p) _NOEXCEPT;
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p, const std::nothrow_t&) _NOEXCEPT;
 #ifndef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
-_LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p, std::size_t __sz) _NOEXCEPT;
+_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void  operator delete(void* __p, std::size_t __sz) _NOEXCEPT;
 #endif
 
 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz) _THROW_BAD_ALLOC;
@@ -190,7 +189,7 @@
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p) _NOEXCEPT;
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p, const std::nothrow_t&) _NOEXCEPT;
 #ifndef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
-_LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p, std::size_t __sz) _NOEXCEPT;
+_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void  operator delete[](void* __p, std::size_t __sz) _NOEXCEPT;
 #endif
 
 #ifndef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
@@ -199,7 +198,7 @@
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p, std::align_val_t) _NOEXCEPT;
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p, std::align_val_t, const std::nothrow_t&) _NOEXCEPT;
 #ifndef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
-_LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete(void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
+_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void  operator delete(void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
 #endif
 
 _LIBCPP_OVERRIDABLE_FUNC_VIS void* operator new[](std::size_t __sz, std::align_val_t) _THROW_BAD_ALLOC;
@@ -207,7 +206,7 @@
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p, std::align_val_t) _NOEXCEPT;
 _LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p, std::align_val_t, const std::nothrow_t&) _NOEXCEPT;
 #ifndef _LIBCPP_HAS_NO_SIZED_DEALLOCATION
-_LIBCPP_OVERRIDABLE_FUNC_VIS void  operator delete[](void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
+_LIBCPP_OVERRIDABLE_FUNC_VIS _LIBCPP_AVAILABILITY_SIZED_NEW_DELETE void  operator delete[](void* __p, std::size_t __sz, std::align_val_t) _NOEXCEPT;
 #endif
 #endif
 
@@ -238,6 +237,9 @@
 
 #ifdef _LIBCPP_BAD_ARRAY_LENGTH_DEFINED
 _LIBCPP_NORETURN inline _LIBCPP_ALWAYS_INLINE
+#ifndef _LIBCPP_NO_EXCEPTIONS
+_LIBCPP_AVAILABILITY_BAD_ARRAY_LENGTH
+#endif
 void __throw_bad_array_length()
 {
 #ifndef _LIBCPP_NO_EXCEPTIONS