[bug#39742] [PATCH 1/7] gnu: java-openjfx-build: Add helpful patch.

[Leo Famulari <leo@famulari.name>]

Hi,

Thanks for these patches and sorry for the delay in review! There are a
lot of patches and it takes a while to get through them.

On Sat, Feb 22, 2020 at 09:17:49PM +0100, Alexey Abramov wrote:
> * gnu/packages/java.scm: Add patch
> * gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch: New
>   file. Allows you to run gradlew to run properly. Useful for debugging.

The commit message needs a couple changes, to something like this:

------
* gnu/packages/patches/java-openjfx-build-get_guix_jdk_version.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/java.scm (java-openjfx-build)[source]: Use it.
------

We don't need to describe the patch in the commit message. Instead, we
explain it in a comment at the beginning of the patch file itself. This
is easier for the people that will read the patch later. The comment
should explain what the patch does and where it came from, including
links to bug reports and external patch sources, if they exist.

We need to register the new patch file in 'gnu/local.mk', so that it
gets distributed in the Guix release process.

And finally, we need to name the package variable (java-openjfx-build)
that the patch is being used by.

Here is an example from an older commit:

https://git.savannah.gnu.org/cgit/guix.git/commit/?id=ca5e404f9a1ff81a38a32578c9c3a6c866482a9a