patch 8.2.3986: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/if_cscope.c b/src/if_cscope.c
index dbaa960..d76f1dd 100644
--- a/src/if_cscope.c
+++ b/src/if_cscope.c
@@ -1105,7 +1105,8 @@
 	// next symbol must be + or -
 	if (strchr(CSQF_FLAGS, *qfpos) == NULL)
 	{
-	    (void)semsg(_("E469: invalid cscopequickfix flag %c for %c"), *qfpos, *(qfpos - 1));
+	    (void)semsg(_(e_invalid_cscopequickfix_flag_chr_for_chr),
+							 *qfpos, *(qfpos - 1));
 	    return FALSE;
 	}