cpp: Added option to disable Zephyrs cpp implementation

Added a Kconfig option to disable Zephyrs cpp implementation for
operator new, delete, pure virtual functions and vtables.

Signed-off-by: Jan Van Winkel <jan.van_winkel@dxplore.eu>

subsys/cpp/CMakeLists.txt

@@ -1,10 +1,15 @@
 # SPDX-License-Identifier: Apache-2.0
 
-zephyr_sources_ifdef(CONFIG_CPLUSPLUS
-  cpp_virtual.c
-  cpp_vtable.cpp
+zephyr_sources(
   cpp_init_array.c
   cpp_ctors.c
   cpp_dtors.c
+)
+
+if (NOT CONFIG_LIB_CPLUSPLUS OR CONFIG_ZEPHYR_CPLUSPLUS)
+zephyr_sources(
+  cpp_virtual.c
+  cpp_vtable.cpp
   cpp_new.cpp
 )
+endif()

subsys/cpp/Kconfig

@@ -65,4 +65,14 @@ config RTTI
 	help
 	  This option enables support of C++ RTTI.
 
+if LIB_CPLUSPLUS
+
+config ZEPHYR_CPLUSPLUS
+	bool "Use Zephyr C++ Implementation"
+	help
+	  Use Zephyr implementation for operator new, delete, pure virtual
+	  functions and vtables.
+
+endif #LIB_CPLUSPLUS
+
 endif # CPLUSPLUS