Nuke SetUpBuildDumpLog.

Also, it was the only reason that `argc` and `argv` were being passed
into createDiagnostics, so remove those parameters and clean up callers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172945 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/diagtool/ShowEnabledWarnings.cpp b/tools/diagtool/ShowEnabledWarnings.cpp
index abd69fd..bcc7520 100644
--- a/tools/diagtool/ShowEnabledWarnings.cpp
+++ b/tools/diagtool/ShowEnabledWarnings.cpp
@@ -71,8 +71,7 @@
 
   // Build the diagnostics parser
   IntrusiveRefCntPtr<DiagnosticsEngine> FinalDiags =
-    CompilerInstance::createDiagnostics(&Invocation->getDiagnosticOpts(),
-                                        argc, argv);
+    CompilerInstance::createDiagnostics(&Invocation->getDiagnosticOpts());
   if (!FinalDiags)
     return NULL;