Add a separate aggressive GC mode

kotlin-native/backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2Native.kt

@@ -293,6 +293,10 @@ class K2Native : CLICompiler<K2NativeCompilerArguments>() {
                         GC.SAME_THREAD_MARK_AND_SWEEP
                     }
                 })
+                if (memoryModel != MemoryModel.EXPERIMENTAL && arguments.gcAggressive) {
+                    configuration.report(ERROR, "-Xgc-aggressive is only supported for -memory-model experimental")
+                }
+                put(GARBAGE_COLLECTOR_AGRESSIVE, arguments.gcAggressive)
             }
         }
     }

kotlin-native/backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2NativeCompilerArguments.kt

@@ -308,6 +308,9 @@ class K2NativeCompilerArguments : CommonCompilerArguments() {
     @Argument(value="-Xgc", valueDescription = "<gc>", description = "GC to use, 'noop' and 'stms' are currently supported. Works only with -memory-model experimental")
     var gc: String? = null
 
+    @Argument(value="-Xgc-aggressive", description = "Make GC agressive. Works only with -memory-model experimental")
+    var gcAggressive: Boolean = false
+
     override fun configureAnalysisFlags(collector: MessageCollector): MutableMap<AnalysisFlag<*>, Any> =
             super.configureAnalysisFlags(collector).also {
                 val useExperimental = it[AnalysisFlags.useExperimental] as List<*>