Use TMPDIR environment variable instead of hardcoding /tmp

src/common/utils.c

@@ -348,12 +348,14 @@ char *_starpu_get_home_path(void)
 	if (!path)
 	{
 		static int warn;
+		path = starpu_getenv("TMPDIR");
+		if (!path)
+			path = "/tmp";
 		if (!warn)
 		{
 			warn = 1;
-			_STARPU_DISP("couldn't find a $STARPU_HOME place to put .starpu data, using /tmp\n");
+			_STARPU_DISP("couldn't find a $STARPU_HOME place to put .starpu data, using %s\n", path);
 		}
-		path = "/tmp";
 	}
 	return path;
 }