Fix function export for msvc build

Author: tobil4sk

src/luasimdjson.h

@@ -1,20 +1,26 @@
 #include <lua.hpp>
+
+#ifdef _MSC_VER
+#define LUASIMDJSON_EXPORT __declspec(dllexport)
+#else
+#define LUASIMDJSON_EXPORT extern
+#endif
+
 extern "C" {
 	static int parse(lua_State*);
 	static int parse_file(lua_State*);
 	static int active_implementation(lua_State*);
 	static int ParsedObject_open(lua_State*);
 	static int ParsedObject_open_file(lua_State*);
 
-
 	static const struct luaL_Reg luasimdjson[] = {
 		{"parse", parse},
 		{"parseFile", parse_file},
 		{"activeImplementation", active_implementation},
 		{"open", ParsedObject_open},
 		{"openFile", ParsedObject_open_file},
-			
+
 		{NULL, NULL},
 	};
-	int luaopen_simdjson (lua_State*);
+	LUASIMDJSON_EXPORT int luaopen_simdjson(lua_State*);
 }