add missing #include


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44282 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/TGLexer.h b/utils/TableGen/TGLexer.h
index 9f1b535..1b157e6 100644
--- a/utils/TableGen/TGLexer.h
+++ b/utils/TableGen/TGLexer.h
@@ -17,6 +17,7 @@
 #include <vector>
 #include <string>
 #include <iosfwd>
+#include <cassert>
 
 namespace llvm {
 class MemoryBuffer;