Prepare for support for CPU binding on other platforms

The interface was Linux/glibc centric, since that is what got there first.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/os/os-linux.h b/os/os-linux.h
index 6812acd..ea2db9b 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -67,6 +67,10 @@
 #endif
 
 #define fio_cpu_clear(mask, cpu)	CPU_CLR((cpu), (mask))
+#define fio_cpu_set(mask, cpu)		CPU_SET((cpu), (mask))
+#define fio_cpuset_init(td)		CPU_ZERO(&(td)->o.cpumask)
+
+#define FIO_MAX_CPUS			CPU_SETSIZE
 
 static inline int ioprio_set(int which, int who, int ioprio)
 {