[C++][Java] Fix ORC Java JNI Crash

[asfimport]

OrcStripeReaderJniWrapper::getSchema previously used nullptr for the memory pool parameter to arrow::ipc::SerializeSchema to implicitly call arrow::default_memory_pool(). As part of https://issues.apache.org/jira/browse/ARROW-10080 a check was placed to fail on nullptr being provided. This change removes the check, but also explicitly calls arrow::default_memory_pool() which is used elsewhere in the JNI wrapper.

Reporter: Terence Honles / @terencehonles
Assignee: Terence Honles / @terencehonles

PRs and other links:

• GitHub Pull Request #8595

_{Note: This issue was originally created as ARROW-10499. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 8595
#8595