[gdb/testsuite] Fix gdb.ada/big_packed_array.exp xfail for -m32

With test-case gdb.ada/big_packed_array.exp and target board unix/-m32 I run
into:
...
(gdb) print bad^M
$2 = (0 => 0 <repeats 24 times>, 160)^M
(gdb) FAIL: gdb.ada/big_packed_array.exp: scenario=minimal: print bad
...

The problem is that while the variable is an array of 196 bits (== 24.5 bytes),
the debug information describes it as 25 unsigned char.  This is PR
gcc/101643, and the test-case contains an xfail for this, which catches only:
...
(gdb) print bad^M
$2 = (0 => 0 <repeats 25 times>)^M
...

Fix this by updating the xfail pattern.

Tested on x86_64-linux.

gdb/testsuite/gdb.ada/big_packed_array.exp

@@ -43,6 +43,7 @@ foreach_with_prefix scenario {all minimal} {
 
     set re "= \\(false <repeats 196 times>\\)"
     set re_xfail "= \\(0 => 0 <repeats 25 times>\\)"
+    set re_xfail2 "= \\(0 => 0 <repeats 24 times>, ($decimal)\\)"
     gdb_test_multiple "print bad" "" {
        -re -wrap $re  {
            pass $gdb_test_name
@@ -54,5 +55,14 @@ foreach_with_prefix scenario {all minimal} {
            }
            fail $gdb_test_name
        }
+       -re -wrap $re_xfail2 {
+	   set last $expect_out(1,string)
+           if { $have_xfail && [string is integer $last] \
+		    && [expr ($last & 0xf) == 0] } {
+               # gcc/101643
+               setup_xfail *-*-*
+           }
+           fail $gdb_test_name
+       }
     }
 }