Amend style switches (expand -gnatyg).

-gnatyg is "check standard GNAT style rules, same as ydISux", but in
GCC 14 it will include a new switch, -gnatyz (check parentheses not
required by operator precedence rules) which will mean that use of
extra parens to clarify intent without deep knowledge of the rules
will trigger fatal warnings; for example in alire-conditional_trees.adb

   function Contains_ORs (This : Tree) return Boolean is
      ((not This.Is_Empty) and then This.Root.Contains_ORs);
       ^

Refer GCC Bugzilla PR 112446.

  * alire_common.gpr (Style_Check_Switches): Remove -gnatyg and replace
    by the pre-GCC 14 equivalent.

alire_common.gpr

@@ -24,9 +24,12 @@ abstract project Alire_Common is
    case Style_Check_Mode is
       when "enabled"  => Style_Check_Switches :=
            ("-gnatwe",   -- Warnings as errors
-            "-gnatyg",   -- Standard checks
+            "-gnatyd",   -- no DOS line terminators
             "-gnatyI",   -- no IN mode
             "-gnatyO",   -- all overrides
+            "-gnatyS",   -- separate lines after THEN/ELSE
+            "-gnatyu",   -- no unnecessary blank lines
+            "-gnatyx",   -- no extra parens around conditionals
             "-gnaty-s"); -- relax fwd decl
       when "disabled" => Style_Check_Switches := ();
    end case;