fix off-by-one computing size for section abbrevs

llvm-svn: 36388
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index b229a76..ea314f6 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -220,7 +220,7 @@
       Abbv->Add(BitCodeAbbrevOp(0));
     else
       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::FixedWidth,
-                               Log2_32_Ceil(SectionMap.size())));
+                               Log2_32_Ceil(SectionMap.size()+1)));
     // Don't bother emitting vis + thread local.
     SimpleGVarAbbrev = Stream.EmitAbbrev(Abbv);
   }