RFR: 8348039: testmake fails at IDEA after JDK-8347825 [v2]

[Magnus Ihse Bursie]

> After JDK-8347825, `test:idea` started failing in the Oracle CI.
> 
> The problem is that when running in the Oracle CI, we are passing `CONF_NAME` to the topmost make. This will result in both `CONF_NAME` and `SPEC` being defined when making the nested make call in the idea.sh script, and this is not allowed.
> 
> I solved this the proper way, by unexporting the variables we have setup during make that could interfere.

Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:

  Update comment
  
  Co-authored-by: Erik Joelsson <37597443+erikj79 at users.noreply.github.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23200/files
  - new: https://git.openjdk.org/jdk/pull/23200/files/daac4fdf..805f879d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23200&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23200&range=00-01

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/23200.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23200/head:pull/23200

PR: https://git.openjdk.org/jdk/pull/23200