Add support for Reason (#3336)

samples/C++/simple.re

@@ -0,0 +1,13 @@
+#define	NULL		((char*) 0)
+char *scan(char *p){
+char *q;
+#define	YYCTYPE		char
+#define	YYCURSOR	p
+#define	YYLIMIT		p
+#define	YYMARKER	q
+#define	YYFILL(n)
+/*!re2c
+	[0-9]+		{return YYCURSOR;}
+	[\000-\377]	{return NULL;}
+*/
+}