the contributed partial fix of KT-35925 set it to the system classloader
which brought in many cases the compiler CP into the evaluation and lead
to the problems like KT-40898. This fix set it to the extension/platform
classloader, which preserves (partial) fix of the KT-35925 and do not
bring the compiler jar into the REPL evaluation classpath.
#KT-40898 fixed
Ilya Chernikov
0a9089bc72