Otherwise, the build will fail when the toolchain is static-only, even
with -Ddefault_library=static. I talked to a Meson developer in their
IRC channel, who told me that the correct fix was to ensure that
shared_library is only used if default_library != static.
We've various macros definitions that are depending using C++ features
that may not work in all the standard versions, so recompile the cxx
tests that we have in all the ones we want to support.
We don't need a cpp toolchain for building glib so lets just
automatically disable tests requiring one when not available.
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>