fixed clang warning

src/data-types/base64.c

@@ -116,8 +116,10 @@ char * decode_base64(const char * in, int len)
     c4 = in[3];
     if (CHAR64(c1) == -1 || CHAR64(c2) == -1 || 
         (c3 != '=' && CHAR64(c3) == -1) || 
-        (c4 != '=' && CHAR64(c4) == -1))
+        (c4 != '=' && CHAR64(c4) == -1)) {
+      free(out);
       return NULL;
+    }
 
     in += 4;
     *output++ = (CHAR64(c1) << 2) | (CHAR64(c2) >> 4);

src/low-level/imf/mailimf.c

@@ -5456,6 +5456,7 @@ int mailimf_msg_id_parse(const char * message, size_t length,
     // ok
   }
   else {
+    free(msg_id);
     res = r;
     goto err;
   }