Build: remove obsolete compiler arguments

These compiler arguments enable features which are enabled by default in
the current Kotlin anyway.

The only exception is in :compiler:cli which uses an old language
version.

compiler/fir/tree/build.gradle.kts

@@ -50,12 +50,6 @@ val compileKotlin by tasks
 
 compileKotlin.dependsOn(generateTree)
 
-tasks.withType<org.jetbrains.kotlin.gradle.dsl.KotlinCompile<*>> {
-    kotlinOptions {
-        freeCompilerArgs += "-Xinline-classes"
-    }
-}
-
 if (kotlinBuildProperties.isInJpsBuildIdeaSync) {
     apply(plugin = "idea")
     idea {