meson.build: add HAVE_GLIB_WITH_ALIGNED_ALLOC flag

meson.build: add HAVE_GLIB_WITH_ALIGNED_ALLOC flag

Rust crates, introduced from the next commit onwards, can optionally use
the glib allocator API and need to know whether g_aligned_alloc etc are
available.

This commit adds a define in config_host_data that depends on glib
version >= 2.72.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/23f7b0cc9801d315f5d7835e30d775e133ec2fb9.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>