patch 8.2.3987: 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 d76f1dd..e0dd759 100644
--- a/src/if_cscope.c
+++ b/src/if_cscope.c
@@ -76,7 +76,7 @@
     static void
 cs_usage_msg(csid_e x)
 {
-    (void)semsg(_("E560: Usage: cs[cope] %s"), cs_cmds[(int)x].usage);
+    (void)semsg(_(e_usage_cscope_str), cs_cmds[(int)x].usage);
 }
 
 static enum
@@ -250,7 +250,7 @@
 
     if (*eap->arg == NUL)
     {
-	(void)emsg(_("E562: Usage: cstag <ident>"));
+	(void)emsg(_(e_usage_cstag_ident));
 	return;
     }
 
@@ -463,7 +463,7 @@
 cs_stat_emsg(char *fname)
 {
     int err = errno;
-    (void)semsg(_("E563: stat(%s) error: %d"), fname, err);
+    (void)semsg(_(e_stat_str_error_nr), fname, err);
 }
 
 
@@ -564,9 +564,8 @@
     else
     {
 	if (p_csverbose)
-	    (void)semsg(
-		_("E564: %s is not a directory or a valid cscope database"),
-		fname);
+	    (void)semsg(_(e_str_is_not_directory_or_valid_cscope_database),
+									fname);
 	goto add_err;
     }
 
@@ -742,7 +741,7 @@
 	search = 9;
 	break;
     default :
-	(void)emsg(_("E561: unknown cscope search type"));
+	(void)emsg(_(e_unknown_cscope_search_type));
 	cs_usage_msg(Find);
 	return NULL;
     }
@@ -799,7 +798,7 @@
     to_cs[0] = to_cs[1] = from_cs[0] = from_cs[1] = -1;
     if (pipe(to_cs) < 0 || pipe(from_cs) < 0)
     {
-	(void)emsg(_("E566: Could not create cscope pipes"));
+	(void)emsg(_(e_could_not_create_cscope_pipes));
 err_closing:
 	if (to_cs[0] != -1)
 	    (void)close(to_cs[0]);
@@ -838,7 +837,7 @@
 	if (!(pipe_stdin = CreatePipe(&stdin_rd, &stdin_wr, &sa, 0))
 		|| !(pipe_stdout = CreatePipe(&stdout_rd, &stdout_wr, &sa, 0)))
 	{
-	    (void)emsg(_("E566: Could not create cscope pipes"));
+	    (void)emsg(_(e_could_not_create_cscope_pipes));
 err_closing:
 	    if (pipe_stdin)
 	    {
@@ -1014,7 +1013,7 @@
 
     if (cs_check_for_connections() == FALSE)
     {
-	(void)emsg(_("E567: no cscope connections"));
+	(void)emsg(_(e_no_cscope_connections));
 	return FALSE;
     }
 
@@ -1356,7 +1355,7 @@
 	    )
 	{
 	    if (p_csverbose)
-		(void)emsg(_("E568: duplicate cscope database not added"));
+		(void)emsg(_(e_duplicate_cscope_database_not_added));
 	    return -1;
 	}
 
@@ -1665,7 +1664,7 @@
 	cs_print_tags_priv(mp, cp, cnt);
 	break;
     default:	// should not reach here
-	iemsg(_("E570: fatal error in cs_manage_matches"));
+	iemsg(_(e_fatal_error_in_cs_manage_matches));
 	return NULL;
     }