Change unistd.h to stddef.h to be correct

size_t should be defined through inclusion of stddef.h instead of unistd.h

Change-Id: Ieaadacfca1e1c44c2533ea95f73fc060c1519b52
diff --git a/libs/utils/StreamingZipInflater.cpp b/libs/utils/StreamingZipInflater.cpp
index c13760a..4e05914 100644
--- a/libs/utils/StreamingZipInflater.cpp
+++ b/libs/utils/StreamingZipInflater.cpp
@@ -20,7 +20,7 @@
 #include <utils/FileMap.h>
 #include <utils/StreamingZipInflater.h>
 #include <string.h>
-#include <unistd.h>
+#include <stddef.h>
 #include <assert.h>
 
 static inline size_t min(size_t a, size_t b) { return (a < b) ? a : b; }