Introduce ansi-c/c_expr.h

This introduces a new header file, ansi-c/c_expr.h, which is to collect
expressions that are specific to and internal to the C frontend.

Author: kroening

src/ansi-c/c_expr.h

@@ -0,0 +1,17 @@
+/*******************************************************************\
+
+Module: API to expression classes that are internal to the C frontend
+
+Author: Daniel Kroening, [email protected]
+
+\*******************************************************************/
+
+#ifndef CPROVER_ANSI_C_C_EXPR_H
+#define CPROVER_ANSI_C_C_EXPR_H
+
+/// \file ansi-c/c_expr.h
+/// API to expression classes that are internal to the C frontend
+
+#include <util/std_code.h>
+
+#endif // CPROVER_ANSI_C_C_EXPR_H