Change hard-coded temporary directory.

The properties tests creates a temporary directory in /data/nativetest,
but this directory might not exist in all circumstances.
Change this to create the temporary directory in /data/local/tmp.

Change-Id: I812d3e24fcd084c5d74055c9faa95b1656f255bc
diff --git a/tests/property_benchmark.cpp b/tests/property_benchmark.cpp
index d10be91..4311a1d 100644
--- a/tests/property_benchmark.cpp
+++ b/tests/property_benchmark.cpp
@@ -32,10 +32,10 @@
     LocalPropertyTestState(int nprops) : nprops(nprops), valid(false) {
         static const char prop_name_chars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ.-_";
 
-        char dir_template[] = "/data/nativetest/prop-XXXXXX";
+        char dir_template[] = "/data/local/tmp/prop-XXXXXX";
         char *dirname = mkdtemp(dir_template);
         if (!dirname) {
-            perror("making temp file for test state failed (is /data/nativetest writable?)");
+            perror("making temp file for test state failed (is /data/local/tmp writable?)");
             return;
         }