cli11: add pkgconfig extsource (#2131)

* cli11: add pkgconfig extsource

* Update xmake.lua

---------

Co-authored-by: ruki <[email protected]>

packages/c/cli11/xmake.lua

@@ -9,6 +9,10 @@ package("cli11")
     add_versions("v2.3.2", "aac0ab42108131ac5d3344a9db0fdf25c4db652296641955720a4fbe52334e22")
     add_versions("v2.2.0", "d60440dc4d43255f872d174e416705f56ba40589f6eb07727f76376fb8378fd6")
 
+    if not is_host("windows") then
+        add_extsources("pkgconfig::CLI11")
+    end
+
     on_install("windows", "linux", "macosx", function (package)
         os.cp("include", package:installdir())
     end)