Rename time.h for third-party include of fio.h

External project might build external ioengines and need to
include there for fio.h. If a project set the include path
to the fio root source directory and the third-party source
holds an "time.h" as well things get complicated.

Signed-off-by: Daniel Gollub <d.gollub@telekom.de>
Cc: Daniel Gollub <daniel.gollub@t-online.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/mutex.c b/mutex.c
index 466e20e..9d10c2c 100644
--- a/mutex.c
+++ b/mutex.c
@@ -15,7 +15,7 @@
 #include "arch/arch.h"
 #include "os/os.h"
 #include "helpers.h"
-#include "time.h"
+#include "fio_time.h"
 #include "gettime.h"
 
 void fio_mutex_remove(struct fio_mutex *mutex)