community/openjdk11: enable s390x again
Error introduced by https://bugs.openjdk.org/browse/JDK-8263718 (https://github.com/openjdk/jdk11u/commit/987f7af5f2186426543f90c328d1ce018c66c37b)
Prior that change, the alloca() call was most likely optimized out by gcc.
Fixed only on OpenJDK17 by https://bugs.openjdk.org/browse/JDK-8267908 (https://github.com/openjdk/jdk/commit/341f676066ab807d433f0f0b6c8356d2ad0e1cc9)
This MR backports the OpenJDK17 fix.