meson: minor simplification

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>

qga/meson.build

@@ -22,12 +22,7 @@ qga_qapi_files = custom_target('QGA QAPI files',
                                depend_files: qapi_gen_depends)
 
 qga_ss = ss.source_set()
-i = 0
-foreach output: qga_qapi_outputs
-  qga_ss.add(qga_qapi_files[i])
-  i = i + 1
-endforeach
-
+qga_ss.add(qga_qapi_files.to_list())
 qga_ss.add(files(
   'commands.c',
   'guest-agent-command-state.c',