Add linux pacman add_extsources for vulkan-tools (#855)

packages/v/vulkan-tools/xmake.lua

@@ -13,7 +13,7 @@ package("vulkan-tools")
 
     add_deps("glslang")
     if is_plat("linux") then
-        add_extsources("apt::vulkan-tools")
+        add_extsources("apt::vulkan-tools", "pacman::vulkan-tools")
         add_deps("wayland", "libxrandr", "libxcb", "libxkbcommon")
     end