`-Xbuild-file` argument allows the compiler to run without
passing any Kotlin source file in arguments.
We have been using this property in
Kotlin Gradle plugin for a few important cases:
1. incremental compilation (to update caches when there are only removed files);
2. for KAPT (Kotlin sources don't make sense in context
of running APs).
We want to stop using `-Xbuild-file` in Kotlin Gradle plugin,
and avoid breaking the Gradle plugin or IC in other build-systems.
This change adds an argument to explicitly run
the compiler without specifying any Kotlin source file.
Alexey Tsvetkov
0687b8eac3