cpp: Add spec of new operator with alignment request

C++17 delivered another specialization of a new operator,
that allows to allocate a memory with requested alignment.

The commit adds these specialziations to C++ subsystem.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>

subsys/cpp/cpp_new.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <stdlib.h>
+#include <new>
 
 #if __cplusplus < 201103L
 #define NOEXCEPT
@@ -32,6 +33,30 @@ void* operator new[](std::size_t size, const std::nothrow_t& tag) NOEXCEPT
 	return malloc(size);
 }
 
+#if __cplusplus >= 201703L
+void* operator new(size_t size, std::align_val_t al)
+{
+	return aligned_alloc(static_cast<size_t>(al), size);
+}
+
+void* operator new[](std::size_t size, std::align_val_t al)
+{
+	return aligned_alloc(static_cast<size_t>(al), size);
+}
+
+void* operator new(std::size_t size, std::align_val_t al,
+		   const std::nothrow_t&) NOEXCEPT
+{
+	return aligned_alloc(static_cast<size_t>(al), size);
+}
+
+void* operator new[](std::size_t size, std::align_val_t al,
+		     const std::nothrow_t&) NOEXCEPT
+{
+	return aligned_alloc(static_cast<size_t>(al), size);
+}
+#endif /* __cplusplus >= 201703L */
+
 void operator delete(void* ptr) NOEXCEPT
 {
 	free(ptr);

subsys/cpp/include/new

@@ -24,6 +24,10 @@ namespace std {
 	};
 #endif /* __cplusplus */
 	extern const std::nothrow_t nothrow;
-}
 
+#if __cplusplus >= 201703L
+	enum class align_val_t : std::size_t {};
+#endif /* CONFIG_STD_CPP17 */
+
+}
 #endif /* ZEPHYR_SUBSYS_CPP_INCLUDE_NEW_ */