Add support for C++ runtime (continue)

[jmi-reds]

Add the support of C++ runtime to SO3. It is the continuation of issue #199.

S03 now uses MUSL as libc for the usr-space and the missing syscall were implemented.

[jmi-reds]

Basic C++ app are working. Tested:

• Hello-world using std::cout
• Simple class - creation, instantiation and a call of a method
• Basic use of std::vector

Problem: the size of the apps are big (around 8.2MB).

[jmi-reds]

The usr app size problem (mentioned above): The app size is due to the .debug_* sections. These sections have been moved to another file

[jmi-reds]

I've added some more basic tests:

• Memory allocation
• exception
• added some more test with the sdlib: map, string to the vector test