Clean up existing entry-point folder existance logic

Previously if you kept running prepare scan without rebuilding the folders would slowly stack up with (#) on the end. This avoids that by only checking for name duplications within the actual results.

Author: JohnDumbell

driver/mkbench.py

@@ -169,6 +169,8 @@ def collect_java_binaries(cmdline):
                    java_binaries.classpath_jar_files +
                    java_libraries.classpath_jar_files +
                    library_directories)
+
+    previously_created_folders = set()
     for ep_data in ep_config["entryPoints"]:
 
         method_data = ep_data["method"]
@@ -183,11 +185,15 @@ def collect_java_binaries(cmdline):
 
         # If our folder exists then just add (#number) to it and try creation again.
         incrementor = 1
-        while os.path.exists(output_folder):
+        while output_folder in previously_created_folders:
             folder_name = friendly_method_name.replace(os.path.sep, '.') + " (" + str(incrementor) + ")"
             output_folder = os.path.join(cmdline.results_dir, folder_name)
             incrementor += 1
 
+        previously_created_folders.add(output_folder)
+        if os.path.exists(output_folder) and os.path.isdir(output_folder):
+            shutil.rmtree(output_folder)
+
         os.mkdir(output_folder)
 
         generated_temp_folder = os.path.join(cmdline.temp_dir, folder_name)