Fix embedding of Xcode action registration

scripts/embed.lua

@@ -7,6 +7,7 @@
 
 
 	local function loadScript(fname)
+		fname = path.getabsolute(fname)
 		local f = io.open(fname)
 		local s = assert(f:read("*a"))
 		f:close()

src/_manifest.lua

@@ -88,5 +88,5 @@
 
 		-- Built-in action modules. The action is registered, but the actual
 		-- implementation is not loaded unless the action is used.
-		"modules/xcode/_action.lua",
+		"../modules/xcode/_action.lua",
 	}