Include what you use: <unistd.h>

This was transitively included, but no longer is, so it must be
explicitly included.

Exempt-From-Owner-Approval: Janitorial
Test: build
Change-Id: I78268a4867697bf797d40b5fead3745fdd0cc807
diff --git a/media/libmedia/MidiIoWrapper.cpp b/media/libmedia/MidiIoWrapper.cpp
index e71ea2c..da272e3 100644
--- a/media/libmedia/MidiIoWrapper.cpp
+++ b/media/libmedia/MidiIoWrapper.cpp
@@ -18,8 +18,9 @@
 #define LOG_TAG "MidiIoWrapper"
 #include <utils/Log.h>
 
-#include <sys/stat.h>
 #include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 #include <media/MidiIoWrapper.h>
 #include <media/MediaExtractorPluginApi.h>