[gcc r17-2957] cobol: Unbreak bootstrap

https://gcc.gnu.org/g:bc1d30b135c199f9f0ac34f7fbde7b876a1aea90

commit r17-2957-gbc1d30b135c199f9f0ac34f7fbde7b876a1aea90
Author: Jakub Jelinek <[email protected]>
Date:   Tue Aug 4 21:38:08 2026 +0200

    cobol: Unbreak bootstrap
    
    Cobol FE uses -Werror=format-diag during bootstrap, so bootstrap
    is currently broken since the recent parse.y change:
    ../../gcc/cobol/parse.y:2188:43: error: unquoted option name '-dialect' in format [-Werror=format-diag]
    
    The following patch fixes that, similarly to other spots that diagnose
    -dialect ibm.
    
    2026-08-04  Jakub Jelinek  <[email protected]>
    
            * parse.y (selected_name): Use %<-dialect ibm%> instead of just
            -dialect ibm.

Diff:
---
 gcc/cobol/parse.y | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/cobol/parse.y b/gcc/cobol/parse.y
index dfd109cee87f..b30d48d1b0b3 100644
--- a/gcc/cobol/parse.y
+++ b/gcc/cobol/parse.y
@@ -2185,7 +2185,7 @@ selected_name:  external NAME {
         |       external OTHER
                 {
                   if( !dialect_ibm() ) {
-                    error_msg(@2, "ASSIGN OTHER requires -dialect ibm");
+                    error_msg(@2, "ASSIGN OTHER requires %<-dialect ibm%>");
                     YYERROR;
                   }