Replace FIO_HAVE_RUSAGE_THREAD with RUSAGE_THREAD

RUSAGE_THREAD is a more clear macro to enable getrusage() thread support.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/os/os-linux.h b/os/os-linux.h
index 2b35f34..9b7ff29 100644
--- a/os/os-linux.h
+++ b/os/os-linux.h
@@ -14,7 +14,6 @@
 #include <linux/unistd.h>
 #include <linux/raw.h>
 #include <linux/major.h>
-#include <linux/version.h>
 #include <endian.h>
 
 #include "indirect.h"
@@ -63,10 +62,6 @@
 #define FIO_HAVE_FALLOC_ENG
 #endif
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
-#define FIO_HAVE_RUSAGE_THREAD
-#endif
-
 #ifdef SYNC_FILE_RANGE_WAIT_BEFORE
 #define FIO_HAVE_SYNC_FILE_RANGE
 #endif
diff --git a/stat.c b/stat.c
index af6e1f2..522901a 100644
--- a/stat.c
+++ b/stat.c
@@ -16,7 +16,7 @@
 {
 	struct thread_stat *ts = &td->ts;
 
-#ifdef FIO_HAVE_RUSAGE_THREAD
+#ifdef RUSAGE_THREAD
 	getrusage(RUSAGE_THREAD, &td->ru_end);
 #else
 	getrusage(RUSAGE_SELF, &td->ru_end);