RFR: 8292717: Clean up checking of testing requirements in configure

[Magnus Ihse Bursie]

I have just moved the code around without changing it, with two exceptions:

* I have updated the names of the functions to match their new home
* I have changed the order in `configure.ac`, so toolchain setup is finished before going on to testing requirements.

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Commit messages:
 - 8292717: Clean up checking of testing requirements in configure

Changes: https://git.openjdk.org/jdk/pull/9964/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9964&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292717
  Stats: 308 lines in 4 files changed: 154 ins; 152 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9964.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9964/head:pull/9964

PR: https://git.openjdk.org/jdk/pull/9964