With this update, we now use our custom `serenity` Clang target, which
means that all system-specific compilation options (e.g. default PIE,
header search paths) will be handled automatically.
This port has been tested to build `Source/little` on all 4
toolchain-architecture pairs. Furthermore, `lib(std)c++` headers are
picked up correctly and our AK headers can be included without any
issues.
Due to recent kernel fixes related to memory-mapped files, the LLD
linker can now be used by default, so there's no need to also build the
GCC port alongside this.
Although our patches cover building libLLVM as a shared library, this is
currently not enabled by default, as DynamicLoader is very slow in
dealing with such a large number of relocations.
We may need entries with spaces in makeopts, installopts, and
configopts, and at that point we should also convert depends and
auth_opts to avoid confusion.
Now that we're generating the CMake toolchain file in the build
directory, we need to redirect the ports that use CMake to the new
location. Looking into this showed that there's still a bunch of work to
do in general to make the ports agnostic to which toolchain they're
using, there's a lot of hard-coded ${ARCH}-pc-serenity-gcc assumptions
still here.
