Fix enum BitcodeError to not define a zero-valued error code.

Summary:
std::error_code assumes it isn't an error if the error code is zero.

Patch by Karl Schimpf

Reviewers: rafael
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D10815

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241933 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Bitcode/ReaderWriter.h

@@ -146,7 +146,7 @@ namespace llvm {
   }
 
   const std::error_category &BitcodeErrorCategory();
-  enum class BitcodeError { InvalidBitcodeSignature, CorruptedBitcode };
+  enum class BitcodeError { InvalidBitcodeSignature = 1, CorruptedBitcode };
   inline std::error_code make_error_code(BitcodeError E) {
     return std::error_code(static_cast<int>(E), BitcodeErrorCategory());
   }