add libc++ and libc++abi sources

upstream: LLVM 10

lib/libcxxabi/src/stdlib_stdexcept.cpp

@@ -0,0 +1,47 @@
+//===------------------------ stdexcept.cpp -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "include/refstring.h"
+#include "stdexcept"
+#include "new"
+#include <cstdlib>
+#include <cstring>
+#include <cstdint>
+#include <cstddef>
+
+static_assert(sizeof(std::__libcpp_refstring) == sizeof(const char *), "");
+
+namespace std  // purposefully not using versioning namespace
+{
+
+logic_error::~logic_error() _NOEXCEPT {}
+
+const char*
+logic_error::what() const _NOEXCEPT
+{
+    return __imp_.c_str();
+}
+
+runtime_error::~runtime_error() _NOEXCEPT {}
+
+const char*
+runtime_error::what() const _NOEXCEPT
+{
+    return __imp_.c_str();
+}
+
+domain_error::~domain_error() _NOEXCEPT {}
+invalid_argument::~invalid_argument() _NOEXCEPT {}
+length_error::~length_error() _NOEXCEPT {}
+out_of_range::~out_of_range() _NOEXCEPT {}
+
+range_error::~range_error() _NOEXCEPT {}
+overflow_error::~overflow_error() _NOEXCEPT {}
+underflow_error::~underflow_error() _NOEXCEPT {}
+
+}  // std