RFR: 8341820: Check return value of hcreate_r

[Matthias Baesken]

In symtab.c there is some coding where hcreate_r is used. We should check the return value of the call (previously there was some guarantee checking the return value but uncommented).

This has been discussed in the PR of [JDK-8341722](https://bugs.openjdk.org/browse/JDK-8341722) .

-------------

Commit messages:
 - JDK-8341820

Changes: https://git.openjdk.org/jdk/pull/21445/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21445&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341820
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/21445.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21445/head:pull/21445

PR: https://git.openjdk.org/jdk/pull/21445