Add wraps for all dependencies

subprojects/packagefiles/libevent-meson/meson.build

-project('Libevent meson wrapper', 'c',
-  meson_version : '>=0.57.0',
-)
-
-mod = import('unstable_external_project')
-
-p = mod.add_project('configure',
-  configure_options : [
-                       '--disable-openssl',
-                      ],
-)
-
-libevent_core_dep = p.dependency('libevent_core')
-if target_machine.system() == 'windows'
-  libevent_windows_dep = p.dependency('libevent_pthreads')
-else
-  libevent_pthreads_dep = p.dependency('libevent_pthreads')
-endif
-