testsuite: Drop needless result reference in testsuite_run().

This holds a reference to the initial result, causing it to linger after
test_result_reset, thereby also holding a reference to the message context,
preventing it from being cleared. This in turn, can keep references to modified
message versions that cause the main message object to remain referenced. This
causes a panic in specific cases upon test_result_reset:

Panic: Input stream data unexpectedly has references

src/testsuite/testsuite.c

@@ -69,9 +69,7 @@ testsuite_run(struct sieve_binary *sbin, struct sieve_error_handler *ehandler)
 
 	/* Run the interpreter */
 	result = testsuite_result_get();
-	sieve_result_ref(result);
 	ret = sieve_interpreter_run(interp, result);
-	sieve_result_unref(&result);
 
 	/* Free the interpreter */
 	sieve_interpreter_free(&interp);

tests/extensions/editheader/execute.svtest

 require "vnd.dovecot.testsuite";
 require "include";
 require "variables";
+require "editheader";
+
+/*
+ * Testsuite self-test
+ */
+
+set "message" ".";
+addheader "X-Some-Header" "Header content";
+test_result_reset;
+test_set "message" "${message}";
 
 /*
  * Multi script
  */
 
+test_result_reset;
+
 test_set "message" text:
 From: idiot@example.com
 To: idiot@example.org