Merge branch 'stable-3.7'

* stable-3.7:
  Add log4j and slf4j-log4j bridge to jgit feature
  Use slf4j to log instead of printing to System.err
  Use Target Platform Definition DSL to generate target platforms

Change-Id: Ic8779868150c910fa55fd20348e35723e6add0f1

diff --cc org.eclipse.jgit.packaging/org.eclipse.jgit.feature/feature.xml
Simple merge

diff --cc org.eclipse.jgit/META-INF/MANIFEST.MF
Simple merge

diff --cc org.eclipse.jgit/pom.xml
Simple merge

diff --cc pom.xml
Simple merge