Adds Gradle test for the exception:
`java.lang.ClassNotFoundException: net.jpountz.lz4.LZ4Factory`
The exception breaks IC in Gradle. Gradle compiles non-incrementally as
a fallback strategy, so the build succeeds, but IC is not working.
IC uses persistent hash tables from Intellij as caches.
These tables's buffers are compressed when full.
Previously snappy was used for compression, but 181 platform switched to
LZ4, which was cut out by proguard.
The problem could only be reproduced with Gradle,
since in JPS plugin all caches are managed by JPS process,
which contains the necessary library.
To reproduce the compiler needs to be processed by proguard
(which always happens on TeamCity).
Many classes are needed to trigger the compression.
Alexey Tsvetkov
38ffd6f85e