patch 8.1.0927: USE_CR is never defined

Problem:    USE_CR is never defined.
Solution:   Remove usage of USE_CR. (Ken Takata, closes #3958)
diff --git a/src/message.c b/src/message.c
index 82772fd..ed59d1b 100644
--- a/src/message.c
+++ b/src/message.c
@@ -2590,10 +2590,7 @@
 		memcpy(buf, p, n);
 		if (!info_message)
 		    buf[n++] = CAR;
-#ifdef USE_CR
-		else
-#endif
-		    buf[n++] = NL;
+		buf[n++] = NL;
 		buf[n++] = NUL;
 		if (info_message)   // informative message, not an error
 		    mch_msg((char *)buf);