[gdb/testsuite] Fix gdb.fortran/array-bounds.exp on arm

[gdb/testsuite] Fix gdb.fortran/array-bounds.exp on arm

When running test-case gdb.fortran/array-bounds.exp on arm-linux, we run into:
...
(gdb) print &foo^M
$1 = (PTR TO -> ( real(kind=4) (0:1) )) 0xfffef008^M
(gdb) FAIL: gdb.fortran/array-bounds.exp: print &foo
print &bar^M
$2 = (PTR TO -> ( real(kind=4) (-1:0) )) 0xfffef010^M
(gdb) FAIL: gdb.fortran/array-bounds.exp: print &bar
...

This is due to gcc PR debug/54934.

The test-case contains a kfail for this, which is only activated for
x86_64/i386.

Fix this by enabling the kfail for all ilp32 targets.

Also:
- change the kfail into an xfail, because gdb is not at fault here, and
- limit the xfail to the gfortran compiler.

Tested on arm-linux.