RFR: 8264449: Enable reproducible builds with SOURCE_DATE_EPOCH

[Kevin Rushforth]

On Thu, 1 Apr 2021 16:50:31 GMT, John Neffenger <jgneff at openjdk.org> wrote:

>> 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?

The WebKit build is complicated (to say the least). All of the WebKit components, including the additional third-party dependencies in `/Source/ThirdParty`, are built using cmake. I think any changes would involve passing flags to cmake in `build.gradle`.

@arun-Joseph might be able to comment on that.

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