OS includes need errno.h

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/os/os-freebsd.h b/os/os-freebsd.h
index 614296a..3939d65 100644
--- a/os/os-freebsd.h
+++ b/os/os-freebsd.h
@@ -1,6 +1,7 @@
 #ifndef FIO_OS_FREEBSD_H
 #define FIO_OS_FREEBSD_H
 
+#include <errno.h>
 #include <sys/sysctl.h>
 
 #define FIO_HAVE_POSIXAIO
diff --git a/os/os-solaris.h b/os/os-solaris.h
index 35148d2..b58d130 100644
--- a/os/os-solaris.h
+++ b/os/os-solaris.h
@@ -1,6 +1,7 @@
 #ifndef FIO_OS_SOLARIS_H
 #define FIO_OS_SOLARIS_H
 
+#include <errno.h>
 #include <sys/types.h>
 #include <sys/fcntl.h>
 #include <sys/pset.h>