test: create temp dir in common.js

For tests run outside the python harness (for example to
see console.error() messages for debugging), common.js
should create the testing temp directory if it does not
exist.

Author: Trott

test/common.js

@@ -20,6 +20,13 @@ if (process.env.TEST_THREAD_ID) {
 }
 exports.tmpDir = path.join(exports.testDir, exports.tmpDirName);
 
+// Create tmpDir if it does not exist
+try {
+  fs.accessSync(exports.tmpDir);
+} catch (err) {
+  fs.mkdirSync(exports.tmpDir);
+}
+
 var opensslCli = null;
 var inFreeBSDJail = null;
 var localhostIPv4 = null;