Perform SWT-natives build as part of the master/verification build

First part of
eclipse-platform#513

The build procedure is based on the configurations in
https://ci.eclipse.org/releng/view/SWT%20Natives/
Namely these are:
- https://ci.eclipse.org/releng/job/SWT-Increment_if_needed/configure
- https://ci.eclipse.org/releng/job/cocoa_aarch64/configure
- https://ci.eclipse.org/releng/job/cocoa_x86_64/configure
- https://ci.eclipse.org/releng/job/gtk_linux_aarch64/configure
- https://ci.eclipse.org/releng/job/gtk_linux_ppc64le/configure
- https://ci.eclipse.org/releng/job/gtk_linux_x86_64/configure
- https://ci.eclipse.org/releng/job/win32_x86_64/configure

The steps of all those jobs are now perform in the Jenkins-build of this
o.e.swt repo and thus makes all the mentioned jobs obsolete. This also
makes building the swt-binaries as part of the I-builds obsolete.
It has also the advantage that one can get immediate feedback in
verification-builds for changes that affect the SWT-binaries.

Signed-off-by: Hannes Wellmann <wellmann.hannes1@gmx.net>