tools: Add dependecy download helpers

This patch adds 2 helpers to download dependencies for compiler and
stub generator during their execution.

They take list of external dependencies as a parameter and directory
where they must be located. Helpers check if these dependencies exist
in the given directory and download not existing ones.

cmd/interop

@@ -40,7 +40,6 @@ findHome() {
 KONAN_HOME="$(findHome)"
 
 NATIVE_LIB="${KONAN_HOME}/konan/nativelib"
-DEPENDENCIES="${KONAN_HOME}/../dependencies/all"
 JAVA_OPTS="-ea \
     -Djava.library.path=${NATIVE_LIB} \
     -Dkonan.home=${KONAN_HOME}"
@@ -49,7 +48,8 @@ STUB_GENERATOR_JAR="${KONAN_HOME}/konan/lib/StubGenerator.jar"
 KOTLIN_JAR="${KONAN_HOME}/konan/lib/kotlin-compiler.jar"
 INTEROP_INDEXER_JAR="${KONAN_HOME}/konan/lib/Indexer.jar"
 INTEROP_RUNTIME_JAR="${KONAN_HOME}/konan/lib/Runtime.jar"
-INTEROP_CLASSPATH="$STUB_GENERATOR_JAR:$KOTLIN_JAR:$INTEROP_INDEXER_JAR:$INTEROP_RUNTIME_JAR"
+HELPERS_JAR="${KONAN_HOME}/konan/lib/helpers.jar"
+INTEROP_CLASSPATH="$STUB_GENERATOR_JAR:$KOTLIN_JAR:$INTEROP_INDEXER_JAR:$INTEROP_RUNTIME_JAR:$HELPERS_JAR"
 INTEROP_TOOL=org.jetbrains.kotlin.native.interop.gen.jvm.MainKt
 
 FLAVOR_ARG=-flavor:native

cmd/konanc

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash 
+#!/usr/bin/env bash
 
 if [ -z "$JAVACMD" -a -n "$JAVA_HOME" -a -x "$JAVA_HOME/bin/java" ]; then
     JAVACMD="$JAVA_HOME/bin/java"
@@ -52,8 +52,9 @@ KONAN_HOME="$(findHome)"
 KONAN_JAR="${KONAN_HOME}/konan/lib/backend.native.jar"
 KOTLIN_JAR="${KONAN_HOME}/konan/lib/kotlin-compiler.jar"
 INTEROP_JAR="${KONAN_HOME}/konan/lib/Runtime.jar"
+HELPERS_JAR="${KONAN_HOME}/konan/lib/helpers.jar"
 NATIVE_LIB="${KONAN_HOME}/konan/nativelib"
-KONAN_CLASSPATH="$KOTLIN_JAR:$INTEROP_JAR:$KONAN_JAR"
+KONAN_CLASSPATH="$KOTLIN_JAR:$INTEROP_JAR:$KONAN_JAR:$HELPERS_JAR"
 KONAN_COMPILER=org.jetbrains.kotlin.cli.bc.K2NativeKt
 JAVA_OPTS=-ea