Samples: Could not create an instance of type org.jetbrains.kotlin.gradle.plugin.KotlinTarget

[ddolovov]

Steps to reproduce:

1. Download fresh K/N samples on your workstation.
2. cd into a sub-project that's not supported on your workstation platform (ex: opengl on Linux or Windows).
3. Run ../gradlew

Expected result: Adequate error message explaining that this project can't be built under current platform.

Actual result:

* What went wrong:
A problem occurred evaluating root project 'opengl'.
> Could not create an instance of type org.jetbrains.kotlin.gradle.plugin.KotlinTarget.
   > Could not find any public constructor for interface org.jetbrains.kotlin.gradle.plugin.KotlinTarget which accepts parameters [java.lang.String].

[ddolovov]

As for now, we've implemented a workaround to fail with more concise exception on attempt to run ../gradlew for not included sub-project:

* What went wrong:
A problem occurred evaluating root project 'win32'.
> Could not get unknown property 'MPPTools' for root project 'win32' of type org.gradle.api.Project.

Better solution should be provided later, when MPPTools will be incorporated into MPP Gradle plugin.