Fix basename usage.

xmake's path.basename has the same name as POSIX basename and Lua's
paths.basename, but does something different.  Switch to the API that
does the right thing.

sdk/xmake.lua

diff --git a/sdk/xmake.lua b/sdk/xmake.lua
index 7170625..bac906e 100644
--- a/sdk/xmake.lua
+++ b/sdk/xmake.lua
@@ -282,7 +282,7 @@
 		simulator = string.gsub(simulator, "${(%w*)}", { sdk=scriptdir, board=boarddir })
 		local firmware = target:targetfile()
 		local directory = path.directory(firmware)
-		firmware = path.basename(firmware)
+		firmware = path.filename(firmware)
 		local run = function(simulator)
 			os.execv(simulator, { firmware }, { curdir = directory })
 		end