Compile built-ins in ForTestCompileRuntime

Remove references to "out/production/builtins", since those built-ins are
compiled by the bootstrap compiler, whereas we want to test built-ins compiled
by the new (working copy) compiler
Compile built-ins with the new compiler in build.xml

Instead of nested "withKotlin" element in javac2 which launches
bootstrap-compiler, we launch K2JVMCompiler from the newly built compiler
directly
Unmark source roots in 'builtins' and 'runtime.jvm'

This is needed because until we have modules and dependencies implemented in
our IDEA plugin, the whole project always is analyzed to highlight any file in
the project. This resulted in weird errors in different modules in Kotlin
project because two declarations were found for each built-in class: the one in
kotlin-runtime.jar and the one (totally unrelated) in the 'builtins' module
Fix built-ins reference resolve tests

Built-in sources are contained now in two directories: compiled and
non-compiled (native). kotlin-plugin.jar has them both under 'jet/', but for
tests we manually specify where to look for the former, as it was for the
latter in LightClassUtil.java