Add missing includes.

Change-Id: I7c6e08c94641709580b765fd3e95b3bb1fa23573
Exempt-From-Owner-Approval: trivial cleanup
Test: mma
Bug: None
diff --git a/hal/acdb.c b/hal/acdb.c
index 99599b8..10d4101 100644
--- a/hal/acdb.c
+++ b/hal/acdb.c
@@ -18,6 +18,7 @@
 //#define LOG_NDEBUG 0
 #define LOG_NDDEBUG 0
 
+#include <errno.h>
 #include <stdlib.h>
 #include <stdbool.h>
 #include <dlfcn.h>