debug/gdb: --disable-sim for CT_GDB_CROSS.

sim was already disabled for CT_GDB_NATIVE.

Reviewed-by: Michael Hope
Signed-off-by: Zhenqiang Chen <zhenqiang.chen@linaro.org>
[yann.morin.1998@anciens.enib.fr: make it a config option]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# m68k specific configuration file

## depends on EXPERIMENTAL

##

## select ARCH_SUPPORTS_32

## select ARCH_DEFAULT_32

## select ARCH_DEFAULT_BE

## select ARCH_SUPPORTS_WITH_CPU

##

## help The m68k architecture