[gcc r13-1471] [Ada] Remove comment about a long gone formal verification mode

[Pierre-Marie de Rodat <pmderodat@gcc.gnu.org>]

https://gcc.gnu.org/g:5b560170323869f7d8406da6c985b0d21b2f7ef3

commit r13-1471-g5b560170323869f7d8406da6c985b0d21b2f7ef3
Author: Piotr Trojanek <trojanek@adacore.com>
Date:   Thu Jun 2 15:10:46 2022 +0200

    [Ada] Remove comment about a long gone formal verification mode
    
    Remove outdated a comment about the very first SPARK experiments
    in GNAT.
    
    gcc/ada/
    
            * sem_ch6.adb (Check_Missing_Return): Remove outdated comment.

Diff:
---
 gcc/ada/sem_ch6.adb | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/gcc/ada/sem_ch6.adb b/gcc/ada/sem_ch6.adb
index 848c2349200..5a4ba7a9290 100644
--- a/gcc/ada/sem_ch6.adb
+++ b/gcc/ada/sem_ch6.adb
@@ -2987,9 +2987,7 @@ package body Sem_Ch6 is
 
       procedure Check_Missing_Return;
       --  Checks for a function with a no return statements, and also performs
-      --  the warning checks implemented by Check_Returns. In formal mode, also
-      --  verify that a function ends with a RETURN and that a procedure does
-      --  not contain any RETURN.
+      --  the warning checks implemented by Check_Returns.
 
       function Disambiguate_Spec return Entity_Id;
       --  When a primitive is declared between the private view and the full