Fix a memory leak in openssh_loadpub

The line read from the input file was not freed after successfully
loading an OpenSSH key.

sshpubk.c

@@ -1091,6 +1091,7 @@ unsigned char *openssh_loadpub(FILE *fp, char **algorithm,
         *commentptr = comment;
     else
         sfree(comment);
+    sfree(line);
     return pubblob;
 
   error: