This commit relocates the "C++ ABI library" components such as
global constructor/destructor and initialiser handlers to a dedicated
directory, `lib/cpp/abi`, in order to provide a clear separation
between the C++ ABI/runtime library and the standard C++ library
components.
Note that the Zephyr C++ ABI library currently implements the GNU/GCC
C++ ABI, which is the de-facto standard ABI used by many compilers
including Clang -- it may be necessary to sub-divide the `lib/cpp/abi`
into `lib/cpp/abi/gnu` and `lib/cpp/abi/someotherabi` in the future
when adding the support for a C++ compiler that expects an ABI vastly
different from the GNU C++ ABI.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
This commit moves the files under `subsys/cpp` directory to the
`lib/cpp` directory because the C++ ABI runtime library and the
standard C++ library components are not a "subsystem" (aka. API) in
conventional sense and is better described as a "library."
Classifying the C++ ABI runtime library and the standard C++ library as
"libraries" instead of "subsystems" also better aligns with how the
existing C standard library implementation (`lib/libc`) is handled.
Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>
