RFR: 8264449: Enable reproducible builds with SOURCE_DATE_EPOCH

[John Neffenger]

On Wed, 31 Mar 2021 13:59:12 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>>> I think there might be a Skara bug.
>> 
>> No, no bug. Sorry about that. I just don't know how GitHub works. :frowning_face: The pre-submit tests ran two days ago when I pushed the branch to GitHub, so by the time I submitted the pull request, they had finished long ago.
>
> I recommend trying this with the following gradle flags, to match the settings for production builds:
> 
> -PCONF=Release -PPROMOTED_BUILD_NUMBER=NNN -PHUDSON_BUILD_NUMBER=MMM -PHUDSON_JOB_NAME=jfx -PCOMPILE_WEBKIT=true -PCOMPILE_MEDIA=true -PBUILD_LIBAV_STUBS=true
> 
> where `NNN` is the promoted build number that is being built (usually taken from the repo tag) and `MMM` is the CI build number. You can just pick any two positive numbers for your test builds.
> 
> Note that this will build the native media libraries and the native webkit library.

@kevinrushforth I found the Makefiles building the media libraries for Windows. I can fix those, but there's also `libxml` and `libxslt` that invoke the Windows linker here:

modules/javafx.web/src/main/native/Source/ThirdParty/libxml/src/win32/Makefile.msvc
modules/javafx.web/src/main/native/Source/ThirdParty/libxslt/src/win32/Makefile.msvc

They both state at the top, "There should never be a need to modify anything below this line." Are those files directly from their upstream sources? If so, what's our policy on patching them while waiting for fixes?

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PR: https://git.openjdk.java.net/jfx/pull/446