Make suite_result creation in update_suite parallel-safe

Author: sim642

scripts/update_suite.rb

@@ -86,7 +86,11 @@ def clearline
 end
 
 $testresults = File.expand_path("tests/suite_result")
-Dir.mkdir($testresults) unless Dir.exist?($testresults)
+begin
+  Dir.mkdir($testresults)
+rescue
+  # exited or was created in parallel
+end
 testfiles    = if incremental then
                  File.expand_path("tests/incremental")
                else