lib: unnecessary header removal for drmtest.h, part 2

I've left unistd.h in it - it's not strictly required but most users
of drmtest.h want it for the open helpers, and then you kinda need to
close that file descriptor again ...

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/pm_rc6_residency.c b/tests/pm_rc6_residency.c
index 3fd9d47e..84eb8a90 100644
--- a/tests/pm_rc6_residency.c
+++ b/tests/pm_rc6_residency.c
@@ -30,6 +30,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
+
 #include "drmtest.h"
 
 #define SLEEP_DURATION 3000 // in milliseconds