samples/portability/cmsis_rtos_v2/philosophers: Exclude qemu_x86_64

This is hitting a stack overflow (probably the same reason xtensa is
also excluded -- both are stack-hungry platforms), but with CMSIS
there is a fixed cap of 512 bytes that can't be extended.  So
whitelist this sample.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
1 file changed