[lit] Fix FormatError on individual test timeout

[mgorny]

Summary

Fix Python FormatError that occurs when lit is trying to output test timeout message. Seems to be broken since r271610

[modocache]

Thank you! I applied this and D25236 locally, and confirmed that they fix a failure I've been seeing in shtest-timeout.py. Thanks, @mgorny!

utils/lit/lit/TestRunner.py

for i,result in enumerate(results):
             out += "note: command had no output on stdout or stderr\n"
 
         # Show the error conditions:
         if result.exitCode != 0:
             out += "error: command failed with exit status: %d\n" % (
                 result.exitCode,)
         if litConfig.maxIndividualTestTime > 0:
             out += 'error: command reached timeout: %s\n' % (
-                i, str(result.timeoutReached))
+                str(result.timeoutReached),)
 
     return out, err, exitCode, timeoutInfo
 
 def executeScript(test, litConfig, tmpBase, commands, cwd):
     bashPath = litConfig.getBashPath();
     isWin32CMDEXE = (litConfig.isWindows and not bashPath)
     script = tmpBase + '.script'
     if isWin32CMDEXE: