Fix off-by-one error in an assert condition. No functionality change, but better
error detection.

llvm-svn: 146962
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 9fc2962..5971011 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -4564,7 +4564,7 @@
   
   unsigned Index = ID - NUM_PREDEF_DECL_IDS;
 
-  if (Index > DeclsLoaded.size()) {
+  if (Index >= DeclsLoaded.size()) {
     Error("declaration ID out-of-range for AST file");
     return 0;
   }