[11u] RFR (XS) 8220718: Missing ResourceMark in nmethod::metadata_do

[Aleksey Shipilev]

Hi,

Please review a small fix in 11u. It cherry-picks the one-liner change that was pushed to 12u in a
much larger one. See the rationale and details in the bug:
  https://bugs.openjdk.java.net/browse/JDK-8220718

Patch:
  http://cr.openjdk.java.net/~shade/8220718/webrev.11u.01/

Testing: tier {1,2,3} locally

Thanks,
-Aleksey