meson: check scdoc version

meson.build

@@ -95,8 +95,9 @@ conf_data.set10('HAVE_SYSTEMD', systemd.found())
 conf_data.set10('HAVE_ELOGIND', elogind.found())
 conf_data.set10('HAVE_TRAY', have_tray)
 
-scdoc = find_program('scdoc', required: get_option('man-pages'))
-if scdoc.found()
+scdoc_dep = dependency('scdoc', version: '>=1.9', native: true, required: get_option('man-pages'))
+if scdoc_dep.found()
+	scdoc = find_program(scdoc_dep.get_pkgconfig_variable('scdoc'))
 	sh = find_program('sh')
 	mandir = get_option('mandir')
 	man_files = [
@@ -126,6 +127,8 @@ if scdoc.found()
 			install_dir: '@0@/man@1@'.format(mandir, section)
 		)
 	endforeach
+else
+	scdoc = disabler()
 endif
 
 add_project_arguments('-DSYSCONFDIR="/@0@"'.format(join_paths(prefix, sysconfdir)), language : 'c')