[UpdateTestChecks] Apply some string concatenation cleanup

Some were what I suggested in D65610.

llvm-svn: 368006
diff --git a/llvm/utils/update_test_checks.py b/llvm/utils/update_test_checks.py
index 5525863..b73e481 100755
--- a/llvm/utils/update_test_checks.py
+++ b/llvm/utils/update_test_checks.py
@@ -78,27 +78,27 @@
   test_paths = []
   for test in args.tests:
     if not glob.glob(test):
-      print('WARNING: Test file \'%s\' was not found. Ignoring it.' % (test,), file=sys.stderr)
+      print("WARNING: Test file '%s' was not found. Ignoring it." % (test,), file=sys.stderr)
       continue
     test_paths.append(test)
 
   for test in test_paths:
     if args.verbose:
-      print('Scanning for RUN lines in test file: %s' % (test,), file=sys.stderr)
+      print('Scanning for RUN lines in test file: %s' + test, file=sys.stderr)
     with open(test) as f:
       input_lines = [l.rstrip() for l in f]
 
     if args.update_only:
       if len(input_lines) == 0 or 'autogenerated' not in input_lines[0]:
-        print('Skipping test which isn\'t autogenerated: %s' % (test), file=sys.stderr)
-        continue;
+        print("Skipping test which isn't autogenerated: " + test, file=sys.stderr)
+        continue
 
     raw_lines = [m.group(1)
                  for m in [common.RUN_LINE_RE.match(l) for l in input_lines] if m]
     run_lines = [raw_lines[0]] if len(raw_lines) > 0 else []
     for l in raw_lines[1:]:
-      if run_lines[-1].endswith("\\"):
-        run_lines[-1] = run_lines[-1].rstrip("\\") + " " + l
+      if run_lines[-1].endswith('\\'):
+        run_lines[-1] = run_lines[-1].rstrip('\\') + ' ' + l
       else:
         run_lines.append(l)
 
@@ -110,9 +110,9 @@
     prefix_list = []
     for l in run_lines:
       if '|' not in l:
-        print('WARNING: Skipping unparseable RUN line: %s' % (l,), file=sys.stderr)
+        print('WARNING: Skipping unparseable RUN line: ' + l, file=sys.stderr)
         continue
-        
+
       (tool_cmd, filecheck_cmd) = tuple([cmd.strip() for cmd in l.split('|', 1)])
       common.verify_filecheck_prefixes(filecheck_cmd)
       if not tool_cmd.startswith(opt_basename + ' '):