RFR: 8325621: Improve jspawnhelper version checks [v3]

[Magnus Ihse Bursie]

On Tue, 12 Mar 2024 19:22:25 GMT, Chad Rakoczy <duke at openjdk.org> wrote:

>> Fix for [8325621](https://bugs.openjdk.org/browse/JDK-8325621)
>> 
>> Updates jspawnhelper to check that JDK version and jspawnhelper version are the same. Updates test to include check for version. Also tested manually by replacing jspawnhelper with incorrect version to confirm that check works.
>
> Chad Rakoczy has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Print to stdout instead of stderr
>  - Compare version using VERSION_STRING

make/modules/java.base/Launcher.gmk line 81:

> 79:       SRC := $(TOPDIR)/src/$(MODULE)/unix/native/jspawnhelper, \
> 80:       OPTIMIZATION := LOW, \
> 81:       CFLAGS := $(CFLAGS_JDKEXE) \

There is no need to introduce a break after `$(CFLAGS_JDKEXE)`, for thing like flags we try to fill the line.
Also, the indentation rules are that a broken line should be indented with four spaces. See e.g. the CFLAGS line below in CoreLibraries.gmk.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/18204#discussion_r1522267500