devel/android-tools-fastboot: shuffle CFLAGS to unbreak DragonFly

Avoid stepping into OS X platform code with off64_t workaround.

cc ... -DAPPLE -DMACH .../ext4_utils/ext4_utils.c
In file included from .../ext4_utils/ext4_utils.c:43:0:
/usr/include/sys/disk.h:49:2: error: #error "This file should not be included by userland programs."
#error "This file should not be included by userland programs."

^

• [ext4_utils.o] Error code 1

Reported by: DPorts