[PATCH] Eliminating static destructor for the BitCodeErrorCategory by converting to a ManagedStatic.

[Chandler Carruth]

Looks good with a small tweak below...

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Comment at: lib/Bitcode/Reader/BitcodeReader.cpp:3508
@@ -3505,3 +3507,3 @@
 const std::error_category &llvm::BitcodeErrorCategory() {
-  static BitcodeErrorCategoryType O;
-  return O;
+  static ManagedStatic<BitcodeErrorCategoryType> O;
+  return *O;
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Since we can't rely on MSVC's thread safe function local statics we have to use a ManagedStatic here... but once we do, on non MSVC we pay the once-init cost twice.

I would just make these globals (sadly) until we only rely on MSVC versions with support for killing managed static entirely.

http://reviews.llvm.org/D5416