print-object: remove spurious new line

[dkochmanski]

Cosmetic fix. Printer is responsible for adding new lines for too expressions by itself what leads to repeating new lines when test results are printed in a list:

> (list
   (lisp-unit:run-tests :all :tests.ce1)
   (lisp-unit:run-tests :all :tests.ce2)
   (lisp-unit:run-tests :all :itests.ce3))
STUB-TEST: 1 assertions passed, 0 failed.

Unit Test Summary
 | 1 assertions total
 | 1 passed
 | 0 failed
 | 0 execution errors
 | 0 missing tests

STUB-TEST: 1 assertions passed, 0 failed.

Unit Test Summary
 | 1 assertions total
 | 1 passed
 | 0 failed
 | 0 execution errors
 | 0 missing tests

STUB-TEST: 0 assertions passed, 1 failed.

Unit Test Summary
 | 1 assertions total
 | 0 passed
 | 1 failed
 | 0 execution errors
 | 0 missing tests

(#<TEST-RESULTS-DB Total(1) Passed(1) Failed(0) Errors(0)>

 #<TEST-RESULTS-DB Total(1) Passed(1) Failed(0) Errors(0)>

 #<TEST-RESULTS-DB Total(1) Passed(0) Failed(1) Errors(0)>
)