Automatic retry for backup, restore, archive-get, and archive-push.

If a local command, e.g. backupFile(), fails it will stop the entire process. Instead, retry local commands to deal with transient errors.

Remove special logic in the S3 storage driver to retry RequestTimeTooSkewed errors since this is now handled by the general retry mechanism in the places where it is most likely to happen, i.e. file read/write. Also, this error should have been entirely eliminated by the asynchronous TLS implementation.

test/src/module/performance/storageTest.c

@@ -228,7 +228,7 @@ testRun(void)
 
                 ProtocolServer *server = protocolServerNew(strNew("storage test server"), strNew("test"), read, write);
                 protocolServerHandlerAdd(server, storageRemoteProtocol);
-                protocolServerProcess(server);
+                protocolServerProcess(server, NULL);
 
             }
             HARNESS_FORK_CHILD_END();