build tools and sdk update

[jasonalmaturner]

Update the Android build tools and sdk to work with React Native 0.56.

[sadafk831]

@jasonalmaturner Thank you for the changes, would you mind making the build tools use the root project versions like following:

def safeExtGet(prop, fallback) {
    rootProject.ext.has(prop) ? rootProject.ext.get(prop) : fallback
}

compileSdkVersion safeExtGet('compileSdkVersion', 26)

[jasonalmaturner]

Totally. That's a much better solution.

[jasonalmaturner]

Should I use safeExtGet for the targetSdkVersion as well?

[skb1129]

Yes, I have seen most of the react-native packages using this on buildToolsVersion and targetSdkVersion as well.

[skb1129]

This is required to be released soon to work with RN 0.56

[daku]

Should this be safeExtGet('targetSdkVersion', 26)?

[daku]

This one needs to be safeExtGet('buildToolsVersion', "26.0.3")

[jasonalmaturner]

Gosh. I'm dumb. Yes. I'll fix that right now.

[p1zzadog]

What's the timeline for this being merged and released? We need this for an upcoming release and I'd like to avoid forking this project.

[4ian]

@tychota @Minishlink @Almouro @AuroreM @chdeps @yleflour Anyone at BAM that could double check this PR and release it? I'm not working on a RN app right now so I have little time for this.

[Minishlink]

Will try to look into this.

In the meantime you can still use the following in your root build.gradle

subprojects { subproject ->
    afterEvaluate{
        if((subproject.plugins.hasPlugin('android') || subproject.plugins.hasPlugin('android-library'))) {
            android {
                compileSdkVersion rootProject.ext.compileSdkVersion
                buildToolsVersion rootProject.ext.buildToolsVersion
            }
        }
    }
}

[jasonalmaturner]

Any other changes need to be made to this pr before it's merged?