Fix a GCC warning, patch by Justin Handville


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@42007 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index a920353..e1829b9 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -57,7 +57,7 @@
   Kind DeclKind   :  8;
   
   /// InvalidDecl - This indicates a semantic error occurred.
-  int InvalidDecl :  1;
+  unsigned int InvalidDecl :  1;
 
 protected:
   Decl(Kind DK) : DeclKind(DK), InvalidDecl(0) {