add pthread for libplist

packages/l/libplist/xmake.lua

@@ -10,6 +10,10 @@ package("libplist")
 
     add_deps("autoconf", "automake", "libtool", "pkg-config")
 
+    if is_plat("linux") then
+        add_syslinks("pthread")
+    end
+
     on_install("macosx", "linux", "mingw", "iphoneos", "cross", function (package)
         local configs = {"--disable-dependency-tracking",
                          "--disable-silent-rules",