[gdb/testsuite] Fix KPASS in gdb.ada/arrayptr.exp

On openSUSE Leap 15.3 I run into:
...
KPASS: gdb.ada/arrayptr.exp: scenario=minimal: print pa_ptr.all \
  (PRMS minimal encodings)
KPASS: gdb.ada/arrayptr.exp: scenario=minimal: print pa_ptr(3) \
  (PRMS minimal encodings)
KPASS: gdb.ada/arrayptr.exp: scenario=minimal: print pa_ptr.all(3) \
  (PRMS minimal encodings)
...

The test-case KFAILs some tests.  However, the analysis in the corresponding
PR talks of a compiler problem, so it should use XFAILs instead.

The KFAILs are setup for pre-gcc-12, but apparantly the fix has been
backported to system compiler 7.5.0, hence the KPASS.

Fix this by:
- using an XFAIL instead of a KFAIL
- matching the specific gdb output that corresponds to the XFAILs
  (reproduced on Fedora 34).

Tested on x86_64-linux, specifically openSUSE Leap 15.3 and Fedora 34.

gdb/testsuite/gdb.ada/arrayptr.exp

@@ -49,27 +49,56 @@ foreach_with_prefix scenario {all minimal} {
 
     gdb_test "ptype string_access" "= access array \\(<>\\) of character"
 
-    set kfail_int128support_re \
-	"That operation is not available on integers of more than 8 bytes\\."
-    set kfail_packed_array_range_re \
+    # GNAT >= 12.0 has the needed fix here.
+    set xfail_expected 0
+    if {$scenario == "minimal" && ![test_compiler_info {gcc-1[2-9]-*}]} {
+	set xfail_expected 1
+    }
+
+    gdb_test_multiple "print pa_ptr.all" "" {
+	-re -wrap " = \\(10, 20, 30, 40, 50, 60, 62, 63, -23, 42\\)" {
+	    pass $gdb_test_name
+	}
+	-re -wrap " = \[0-9\]+" {
+	    if { $xfail_expected } {
+		xfail $gdb_test_name
+	    } else {
+		fail $gdb_test_name
+	    }
+	}
+    }
+
+    set xfail_cannot_subscript_re \
 	"cannot subscript or call something of type `foo__packed_array_ptr'"
 
-    # GNAT >= 12.0 has the needed fix here.
-    if {$scenario == "minimal" && ![test_compiler_info {gcc-1[2-9]-*}]} {
-	setup_kfail "minimal encodings" *-*-*
-    }
-    gdb_test "print pa_ptr.all" \
-	" = \\(10, 20, 30, 40, 50, 60, 62, 63, -23, 42\\)"
+    gdb_test_multiple "print pa_ptr(3)" "" {
+	-re -wrap " = 30" {
+	    pass $gdb_test_name
 
-    # GNAT >= 12.0 has the needed fix here.
-    if {$scenario == "minimal" && ![test_compiler_info {gcc-1[2-9]-*}]} {
-	setup_kfail "minimal encodings" *-*-*
 	}
-    gdb_test "print pa_ptr(3)" " = 30"
+	-re -wrap $xfail_cannot_subscript_re {
+	    if { $xfail_expected } {
+		xfail $gdb_test_name
+	    } else {
+		fail $gdb_test_name
+	    }
+	}
+    }
+
+    set xfail_attempt_to_index_re \
+	"Attempt to index or call something other than an array or function"
+
+    gdb_test_multiple "print pa_ptr.all(3)" "" {
+	-re -wrap " = 30" {
+	    pass $gdb_test_name
 
-    # GNAT >= 12.0 has the needed fix here.
-    if {$scenario == "minimal" && ![test_compiler_info {gcc-1[2-9]-*}]} {
-	setup_kfail "minimal encodings" *-*-*
 	}
-    gdb_test "print pa_ptr.all(3)" " = 30"
+	-re -wrap $xfail_attempt_to_index_re {
+	    if { $xfail_expected } {
+		xfail $gdb_test_name
+	    } else {
+		fail $gdb_test_name
+	    }
+	}
+    }
 }