bam.lua: Add "intermediate" directory to paths and use it when building object files.

bam.lua

@@ -24,9 +24,15 @@ end
 
 -- paths used when building.
 paths = {
-	build		= ScriptArgs.build_dir or "build",
-	object 		= "obj",
-	examples 	= "examples"
+	-- Root build directory.
+	build		 = ScriptArgs.build_dir or "build",
+
+	-- Directory where internal object/libs files are
+	-- stored to produce the final library.
+	intermediate = PathJoin("spectre", TARGET_OS),
+
+	object 		 = "obj",
+	examples 	 = "examples"
 }
 
 --------------------------------
@@ -59,7 +65,8 @@ global_settings.link.Output = function(settings, input)
 end
 
 global_settings.cc.Output = function(settings, input)
-	return Path(PathJoin(PathJoin(paths.build, paths.object), PathBase(input)))
+	local path = PathJoin(paths.build, paths.intermediate)
+	return Path(PathJoin(PathJoin(path, paths.object), PathBase(input)))
 end
 
 -- Compiler configuration