Remove duplicated sources of built-ins

BuiltInsSerializer now serializes built-ins found in two source roots:
core/builtins/native and core/builtins/src

Add return types to some declarations in core/builtins/src, because now that
BuiltInsSerializer processes them, it launches lazy resolution which can't
always deduce the return type
Don't fail on annotated built-ins

Unit.VALUE is annotated right now (with "suppress"), so deserialization was
throwing an exception from AnnotationDeserializer.UNSUPPORTED. Return empty
collections of annotations instead; here we use the fact that it's the only
annotation in built-ins and its presence is useless to the type checker
Update test data after introduction of compilable built-ins

'next()' in primitive iterators is now final, as it always was in module
'runtime' before
Serialize built-ins on 'ant dist'

Don't store binary data in the repository anymore. From now on any test on the
compiler requires that 'ant dist' was executed at least once since the last
update of the built-ins
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.

Simplify code in JetReferenceUtil to have almost the same meaning as in
JetPsiReference.multiResolve()