Vivado/HLS: delete logfile before watching

src/main/scala/tapasco/activity/composers/VivadoComposer.scala

@@ -66,6 +66,7 @@ class VivadoComposer()(implicit cfg: Configuration) extends Composer {
                 composition  = composition(bd, target))
 
     logger.info("Vivado starting run {}: output in {}", files.runName: Any, files.logFile)
+    files.logFile.toFile.delete
     cfg.verbose foreach { mode =>
       logger.info("verbose mode {} is active, starting to watch {}", mode: Any, files.logFile)
       lt += files.logFile

src/main/scala/tapasco/activity/hls/VivadoHighLevelSynthesis.scala

@@ -55,6 +55,7 @@ private object VivadoHighLevelSynthesis extends HighLevelSynthesizer {
       new FileWriter(script.toString).append(makeScript(k, t)).close()  // write Tcl file
       val runName = "'%s' for %s".format(k.name, t.toString)
       logger.info("starting run {}: output in {}", runName: Any, logfile)
+      logfile.toFile.delete
       cfg.verbose foreach { mode =>
         logger.info("verbose mode {} is active, starting to watch {}", mode: Any, logfile)
         lt += logfile