Fix a few memory leaks.

Mostly noticed in passing while using Address / Leak Sanitiser to
check over the previous commit. One highlight here is freeing of the
previous iqmp value in rsa_verify, which was actually a potentially
sensitive leak, introduced in the mp_int rewrite (commit 25b034ee3).

cmdgen.c

@@ -1072,6 +1072,9 @@ int main(int argc, char **argv)
 	ssh_key_free(ssh2key->key);
 	sfree(ssh2key);
     }
+    sfree(origcomment);
+    if (infilename)
+        filename_free(infilename);
     filename_free(outfilename);
 
     return 0;

settings.c

@@ -519,6 +519,7 @@ static void read_clip_setting(settings_r *sesskey, char *savekey,
         val = CLIPUI_NONE;
     }
     conf_set_int(conf, confkey, val);
+    sfree(setting);
 }
 
 char *save_settings(const char *section, Conf *conf)

ssh2transhk.c

@@ -66,6 +66,7 @@ void ssh_transient_hostkey_cache_free(ssh_transient_hostkey_cache *thc)
         sfree(ent);
     }
     freetree234(thc->cache);
+    sfree(thc);
 }
 
 void ssh_transient_hostkey_cache_add(

sshprime.c

@@ -451,6 +451,7 @@ void invent_firstbits(unsigned *one, unsigned *two, unsigned min_separation)
     }
 
     mp_free(randval);
+    mp_free(total);
 
     /*
      * Check everything came out right.

sshrsa.c

@@ -332,6 +332,7 @@ bool rsa_verify(RSAKey *key)
     mp_int *q_new = mp_min(key->p, key->q);
     mp_free(key->p);
     mp_free(key->q);
+    mp_free(key->iqmp);
     key->p = p_new;
     key->q = q_new;
     key->iqmp = mp_invert(key->q, key->p);