[ruby/stringio] Fixed a typo

b249631c43 (commitcomment-34804150)

https://github.com/ruby/stringio/commit/998d6257fb

ext/stringio/stringio.c

@@ -303,7 +303,7 @@ detect_bom(VALUE str, int *bomlen)
 
       case 0:
 	if (len < 4) break;
-	if ((unsigned char)p[1] == 0 && (unsigned char)p[2] == 0xFE & (unsigned char)p[3] == 0xFF) {
+	if ((unsigned char)p[1] == 0 && (unsigned char)p[2] == 0xFE && (unsigned char)p[3] == 0xFF) {
 	    *bomlen = 4;
 	    return rb_enc_find_index("UTF-32BE");
 	}