Fix mac build

"errno.h" doesn't get included on mac so we need to do it explicitely.

system/core/libnativebridge/tests/CodeCacheExists_test.cpp:30:15: error:
use of undeclared identifier 'ENOENT'
      ASSERT_EQ(ENOENT, errno);

(cherry picked from commit bcd1a834d4a979ae650ac8677b0647cfb3ec4766)

Change-Id: Ib894e3a3912a943c61787461f127e4b11aacf212
diff --git a/libnativebridge/tests/CodeCacheCreate_test.cpp b/libnativebridge/tests/CodeCacheCreate_test.cpp
index 6aa8eaa..58270c4 100644
--- a/libnativebridge/tests/CodeCacheCreate_test.cpp
+++ b/libnativebridge/tests/CodeCacheCreate_test.cpp
@@ -16,6 +16,7 @@
 
 #include "NativeBridgeTest.h"
 
+#include <errno.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
diff --git a/libnativebridge/tests/CodeCacheExists_test.cpp b/libnativebridge/tests/CodeCacheExists_test.cpp
index 43f8d9c..8ba0158 100644
--- a/libnativebridge/tests/CodeCacheExists_test.cpp
+++ b/libnativebridge/tests/CodeCacheExists_test.cpp
@@ -16,6 +16,7 @@
 
 #include "NativeBridgeTest.h"
 
+#include <errno.h>
 #include <sys/stat.h>
 #include <unistd.h>