To ensure size_t same as toolchain definition in the first place and rename CXX_NEWLONG to ARCH_SIZET_LONG. The change also check whether __SIZE_TYPE__ exist before CONFIG_ARCH_SIZET_LONG so our definition can align with toolchain(gcc/clang) definition automatically.
Squashed commit of the following:
libs/libxx: Fix some confusing in naming. If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
libs/: Fix paths in moved library directories.
libs: Brute force move of libc, libnx, and libxx to libs. Cannot yet build it in that configuration.