[15] RFR[T] 8246075: Missing logging in nmethod::oops_do_marking_epilogue() on early return path

[Zhengyu Gu]

Please review this trivial patch that ensures 
ops_do_marking_prologue/epilogue messages are matched.

Bug: https://bugs.openjdk.java.net/browse/JDK-8246075
Webrev: http://cr.openjdk.java.net/~zgu/JDK-8246075/webrev.00/

Test:
   tier1 on Linux x86_64
   Submit test in progress

Thanks,

-Zhengyu