emulators/unicorn: fix build on powerpc64*

In file included from /wrkdirs/usr/ports/emulators/unicorn/work/unicorn-2.1.4/qemu/util/bitmap.c:13:
In file included from /wrkdirs/usr/ports/emulators/unicorn/work/unicorn-2.1.4/qemu/include/qemu/bitops.h:16:
In file included from /wrkdirs/usr/ports/emulators/unicorn/work/unicorn-2.1.4/qemu/include/qemu/host-utils.h:30:
/wrkdirs/usr/ports/emulators/unicorn/work/unicorn-2.1.4/qemu/include/qemu/int128.h:150:16: error: typedef redefinition with different types ('Int128' (aka 'struct Int128') vs '__int128')