Forward declare Instruction enum in EVMVersion

liblangutil/EVMVersion.cpp

@@ -20,6 +20,7 @@
  */
 
 #include <liblangutil/EVMVersion.h>
+#include <libevmasm/Instruction.h>
 
 using namespace solidity;
 using namespace solidity::evmasm;

liblangutil/EVMVersion.h

@@ -21,14 +21,18 @@
 
 #pragma once
 
-#include <libevmasm/Instruction.h>
-
 #include <optional>
 #include <string>
 
 #include <boost/operators.hpp>
 
 
+namespace solidity::evmasm
+{
+/// Virtual machine bytecode instruction. Forward declared from libevmasm/Instruction.h
+enum class Instruction: uint8_t;
+}
+
 namespace solidity::langutil
 {