RFR: 8325567: jspawnhelper without args fails with segfault [v8]

[Elif Aslan]

> This change is intended to address the segmentation fault issue that occurs when jspawnhelper is called without arguments,.
> There is a new test added  to verify the behavior in such cases.
> 
> `[ec2-user at ip-172-16-0-10 jdk]$ make CONF=linux-x86_64-server-fastdebug test TEST=test/jdk/java/lang/ProcessBuilder/JspawnhelperWarnings.java`
> 
> 
> 
> ==============================
> Test summary
> ==============================
>    TEST                                              TOTAL  PASS  FAIL ERROR
>    jtreg:test/jdk/java/lang/ProcessBuilder/JspawnhelperWarnings.java
>                                                          1     1     0     0
> ==============================
> TEST SUCCESS

Elif Aslan has updated the pull request incrementally with one additional commit since the last revision:

  Address comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18112/files
  - new: https://git.openjdk.org/jdk/pull/18112/files/c82fb77b..ef321d2c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18112&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18112&range=06-07

  Stats: 3 lines in 1 file changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18112.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18112/head:pull/18112

PR: https://git.openjdk.org/jdk/pull/18112