[Native] Add simple symbol mechanism to konan.properties

Java Properties format is extremely trivial and does not support any
kind of references or variables. It makes konan.properties repetitive.
This commits adds support of perl-like `$` sigil which allows to
reference properties inside values.

compiler/util-io/src/org/jetbrains/kotlin/konan/properties/Properties.kt

@@ -69,3 +69,51 @@ fun Properties.keepOnlyDefaultProfiles() {
     // TODO: it actually affects only resolution made in :dependencies,
     // that's why we assume that 'default' profile comes first (and check this above).
 }
+
+
+/**
+ * Wraps [propertyList] with resolving mechanism. See [String.resolveValue].
+ */
+fun Properties.resolvablePropertyList(
+    key: String, suffix: String? = null, escapeInQuotes: Boolean = false,
+    visitedProperties: MutableSet<String> = mutableSetOf()
+): List<String> = propertyList(key, suffix, escapeInQuotes).flatMap {
+    // We need to create a copy of a visitedProperties to avoid collisions
+    // between different elements of the list.
+    it.resolveValue(this, visitedProperties.toMutableSet())
+}
+
+/**
+ * Wraps [propertyString] with resolving mechanism. See [String.resolveValue].
+ */
+fun Properties.resolvablePropertyString(
+    key: String, suffix: String? = null,
+    visitedProperties: MutableSet<String> = mutableSetOf()
+): String? = propertyString(key, suffix)
+    ?.split(' ')
+    ?.flatMap { it.resolveValue(this, visitedProperties) }
+    ?.joinToString(" ")
+
+/**
+ * Adds trivial symbol resolving mechanism to properties files.
+ *
+ * Given the following properties file:
+ *
+ *      key0 = value1 value2
+ *      key1 = value3 $key0
+ *      key2 = $key1
+ *
+ * "$key1".resolveValue(properties) will return List("value3", "value1", "value2")
+ */
+private fun String.resolveValue(properties: Properties, visitedProperties: MutableSet<String> = mutableSetOf()): List<String> =
+    when {
+        startsWith("$") -> {
+            val property = this.substringAfter('$')
+            // Keep track of visited properties to avoid running in circles.
+            if (!visitedProperties.add(property)) {
+                error("Circular dependency: ${visitedProperties.joinToString()}")
+            }
+            properties.resolvablePropertyList(property, visitedProperties = visitedProperties)
+        }
+        else -> listOf(this)
+    }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/compilerRunner/nativeToolRunners.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider
 import org.jetbrains.kotlin.gradle.plugin.mpp.isAtLeast
 import org.jetbrains.kotlin.gradle.utils.NativeCompilerDownloader
 import org.jetbrains.kotlin.konan.CompilerVersion
+import org.jetbrains.kotlin.konan.properties.resolvablePropertyString
 import org.jetbrains.kotlin.konan.target.HostManager
 import org.jetbrains.kotlin.konan.target.KonanTarget
 import org.jetbrains.kotlin.konan.util.DependencyDirectories
@@ -104,7 +105,7 @@ internal abstract class AbstractKotlinNativeCInteropRunner(toolName: String, pro
                 project.file("${project.konanHome}/konan/konan.properties").inputStream().use(::load)
             }
 
-            konanProperties.getProperty("llvmHome.mingw_x64")?.let { toolchainDir ->
+            konanProperties.resolvablePropertyString("llvmHome.mingw_x64")?.let { toolchainDir ->
                 DependencyDirectories.defaultDependenciesRoot
                     .resolve("$toolchainDir/bin")
                     .absolutePath

native/utils/src/org/jetbrains/kotlin/konan/target/Distribution.kt

@@ -43,6 +43,10 @@ class Distribution(
     fun additionalPropertyFiles(genericName: String) =
         preconfiguredPropertyFiles(genericName) + userPropertyFiles(genericName)
 
+    /**
+     * Please note that konan.properties uses simple resolving mechanism.
+     * See [org.jetbrains.kotlin.konan.properties.resolveValue].
+     */
     val properties by lazy {
         val result = Properties()