unix-socket: fix shadowed variable

ret does not need to be redefined here, the existing
declaration of ret can be used.

src/unix-manager.c

@@ -127,7 +127,6 @@ int UnixNew(UnixCommand * this)
         struct stat stat_buf;
         /* coverity[toctou] */
         if (stat(SOCKET_PATH, &stat_buf) != 0) {
-            int ret;
             /* coverity[toctou] */
             ret = mkdir(SOCKET_PATH, S_IRWXU|S_IXGRP|S_IRGRP);
             if (ret != 0) {