Add a magic LLVM_DISABLE_CRT_DEBUG environment variable which we check in RegisterHandler and use to disable the Win32 crash dialogs. These are a major blocker to any kind of automated testing.

Also, tweak the 'lit' test runner to set this variable unconditionally.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82537 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/lit/TestingConfig.py b/utils/lit/TestingConfig.py
index bfe23b2..e4874d7 100644
--- a/utils/lit/TestingConfig.py
+++ b/utils/lit/TestingConfig.py
@@ -13,6 +13,7 @@
                 'PATH' : os.pathsep.join(litConfig.path +
                                          [os.environ.get('PATH','')]),
                 'SYSTEMROOT' : os.environ.get('SYSTEMROOT',''),
+                'LLVM_DISABLE_CRT_DEBUG' : '1',
                 }
 
             config = TestingConfig(parent,