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/libaaudio/src/utility/AAudioUtilities.h b/media/libaaudio/src/utility/AAudioUtilities.h
index 76d0457..0dd866d 100644
--- a/media/libaaudio/src/utility/AAudioUtilities.h
+++ b/media/libaaudio/src/utility/AAudioUtilities.h
@@ -21,6 +21,7 @@
 #include <functional>
 #include <stdint.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #include <utils/Errors.h>
 #include <system/audio.h>