java/openjdk11: fix build on 32 bit arm

Slightly adjusted the patch of Mikael Urankar to make sure it only
affects arm builds.
The patch is similar to what fixed openjdk8 in
commit e13c81137266603a6a0700810b6bad419f9d98c8.

Not bumping portrevision as nothing changes for existing pkgs.

PR: 255662
Approved by: java@ (maintainer timeout)