meson: convert hw/arch*

Each architecture's sourceset is placed in an hw_arch dictionary, and picked up
from there when building the per-emulator static_library.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/meson.build b/meson.build
index ec958ba..5c9f66d 100644
--- a/meson.build
+++ b/meson.build
@@ -787,6 +787,10 @@
   if target.endswith('-softmmu')
     qemu_target_name = 'qemu-system-' + target_name
     target_type='system'
+    hw_dir = target_name == 'sparc64' ? 'sparc64' : arch
+    hw = hw_arch[hw_dir].apply(config_target, strict: false)
+    arch_srcs += hw.sources()
+
     arch_srcs += config_devices_h[target]
   else
     target_type='user'