RFR: 8264449: Enable reproducible builds with SOURCE_DATE_EPOCH

[Kevin Rushforth]

On Thu, 1 Apr 2021 17:22:16 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> @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.

I should add that if changes are needed to the `Makefile.msvc` files to accept extra link flags to be passed in, then it would be fine to modify them.

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