issue #2607, enable '\e' character escape for --standard cc65

test/standard/issue2607_cc65.c

@@ -0,0 +1,14 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/* this should succeed on all three standards
+ * yet use only \e on CC65
+ */
+int main(void) {
+
+#if __CC65_STD__ == __CC65_STD_CC65__
+    printf("\e");
+#endif
+
+    return EXIT_SUCCESS;
+}