libyaml: add_extsources pkgconfig::yaml-0.1 (#7261)

packages/l/libyaml/xmake.lua

@@ -9,6 +9,10 @@ package("libyaml")
     add_versions("0.2.2", "46bca77dc8be954686cff21888d6ce10ca4016b360ae1f56962e6882a17aa1fe")
     add_versions("0.2.5", "fa240dbf262be053f3898006d502d514936c818e422afdcf33921c63bed9bf2e")
 
+    if not is_subhost("windows") then
+        add_extsources("pkgconfig::yaml-0.1")
+    end
+
     on_load("windows", function (package)
         if not package:config("shared") then
             package:add("defines", "YAML_DECLARE_STATIC")