Update xmake.lua (#1346)

packages/c/cxxopts/xmake.lua

@@ -8,6 +8,14 @@ package("cxxopts")
     add_versions("v3.0.0", "36f41fa2a46b3c1466613b63f3fa73dc24d912bc90d667147f1e43215a8c6d00")
     add_versions("v2.2.0", "447dbfc2361fce9742c5d1c9cfb25731c977b405f9085a738fbd608626da8a4d")
 
+    if is_plat("mingw") and is_subhost("msys") then
+        add_extsources("pacman::cxxopts")
+    elseif is_plat("linux") then
+        add_extsources("pacman::cxxopts-git", "apt::libcxxopts-dev")
+    elseif is_plat("macosx") then
+        add_extsources("brew::cxxopts")
+    end
+
     on_install(function (package)
         os.cp("include/*.hpp", package:installdir("include"))
     end)