RFR: JDK-8180281 --with-jtreg is broken for many use cases

[Magnus Ihse Bursie]

It turned out that run-test behaved badly when JT_HOME was not set. 
Here's an updated version with a more helpful failure mode.

http://cr.openjdk.java.net/~ihse/JDK-8180281-with-jtreg-is-broken/webrev.02

/Magnus

On 2017-05-12 12:08, Magnus Ihse Bursie wrote:
> JDK-8179537 was opened with a request to document the brokenness of 
> --with-jtreg. Better to fix it than to document how it's broken.
>
> Now --with-jtreg works like this:
>  * --without-jtreg will explicitly disable jtreg.
>  * --with-jtreg=<jtreg home> will use the specified directory, and 
> will do sanity checks that it is indeed a jtreg home pointed to, and 
> not a binary.
> * When no option is given, we try to locate jtreg using JT_HOME from 
> the environment, and, failing that, by finding the jtreg executable in 
> the path and deriving a JT_HOME from that. If not found, jtreg will be 
> disabled.
> * --with-jtreg (with no arguments) will try to locate jtreg 
> automatically as described above, but if it fails, it will abort 
> configure.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8180281
> WebRev: 
> http://cr.openjdk.java.net/~ihse/JDK-8180281-with-jtreg-is-broken/webrev.01
>
> /Magnus