Add linux pacman add_extsources for xtrans (#851)

packages/x/xtrans/xmake.lua

@@ -7,7 +7,7 @@ package("xtrans")
     add_versions("1.4.0", "377c4491593c417946efcd2c7600d1e62639f7a8bbca391887e2c4679807d773")
 
     if is_plat("linux") then
-        add_extsources("apt::xtrans-dev")
+        add_extsources("apt::xtrans-dev", "pacman::xtrans")
     end
 
     if is_plat("macosx", "linux") then