debug/gdb: always enable expat for the cross-gdb

There's no point in not supporting XML in the cross-gdb.
I mean, come on... ;-)

It's still the responsibility of the user to have the necessary
devel expat packages installed for his/her distro.

Reported-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

CT_EXPERIMENTAL=y

CT_LOCAL_TARBALLS_DIR="${HOME}/src"

CT_SAVE_TARBALLS=y

CT_CONFIG_SHELL_SH=y

CT_LOG_EXTRA=y

CT_ARCH_avr32=y

CT_BINUTILS_V_2_18a=y

CT_CC_V_4_2_2=y

CT_LIBC_NEWLIB_V_1_17_0=y