[lit] Print exit code in for unresolved (lldb)tests.

[JDevlieghere]

Summary

A test is marked unresolved when we're unable to find PASSED or FAILED
in the dotest output. Usually this is because we crashed and when that
happens the exit code can give a clue as to why. This patch adds the
exit code to the lit output to make it easier to investigate those
issues.

[aprantl]

If it helps...
Is there anything else we can print for a crashed dotest?

[JDevlieghere]

In D66975#1651757, @aprantl wrote:

If it helps...
Is there anything else we can print for a crashed dotest?

Is there anything else other than stdout, stderr and the exit code?

lldb/trunk/lit/Suite/lldbtest.py

def execute(self, test, litConfig):
                 if line.startswith('FAIL:'):
                     return lit.Test.FAIL, out + err
 
             if 'XPASS:' in out or 'XPASS:' in err:
                 return lit.Test.XPASS, out + err
 
         passing_test_line = 'RESULT: PASSED'
         if passing_test_line not in out and passing_test_line not in err:
-            msg = ('Unable to find %r in dotest output:\n\n%s%s' %
-                   (passing_test_line, out, err))
+            msg = ('Unable to find %r in dotest output (exit code %d):\n\n%s%s'
+                   % (passing_test_line, exitCode, out, err))
             return lit.Test.UNRESOLVED, msg
 
         return lit.Test.PASS, ''