Speed up build by avoiding gradle-api.jar generation

[raphiz]

Not sure yet if that's a good Idea but Gradle initially generates a gradle-api.jar which is then stored in GRADLE_HOME/.gradle/caches/8.7/generated-gradle-jars/gradle-api-8.7.jar (depending on the version, here 8.7). This can take 10-20 seconds depending on your machine.