Don't reference "compile" when it's not present

[Namnodorel]

In the latest Android Gradle Plugin Canary, compile has been removed in favor of implementation and api. That results in this line failing during build:

gradle-maven-plugin/artifact-pom-manager.gradle

Line 86 in c40e90e

configurations.compile.getDependencies().each { dep -> addDependency(dep, "compile") }

Execution failed for task ':views:generatePomFileForMavenPublishPublication'.
> Could not apply withXml() to generated POM
   > Could not get unknown property 'compile' for configuration container of type org.gradle.api.internal.artifacts.configurations.DefaultConfigurationContainer.

I don't know much about Groovy syntax, but I think adding a check before accessing the property should quickly solve this problem.