Included assert.h so that the code compiles under newer versions of GCC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6682 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/InstVisitor.h

@@ -44,6 +44,8 @@
 #define LLVM_SUPPORT_INSTVISITOR_H
 
 #include "llvm/Instruction.h"
+#include <assert.h>
+
 class Module;
 
 // We operate on opaque instruction classes, so forward declare all instruction