Remove runtime jar files version checker

... and the compiler argument -Xskip-runtime-version-check.

The vast majority of warnings reported by this checker in practice has
proven to be false positives. In addition to that, it was needlessly
verbose, and also completely untested.

If we decide to reintroduce some of these checks, it's probably a better
idea to perform them in tools, such as Kotlin Gradle plugin, which
usually have slightly more information about the way the project is
built and can suggest some meaningful solutions (as opposed to "remove
this jar $HOME/.gradle/... from the classpath" which was the best
JvmRuntimeVersionsConsistencyChecker could do.)

 #KT-27256 Obsolete
 #KT-41664 Fixed

compiler/config.jvm/src/org/jetbrains/kotlin/config/JVMConfigurationKeys.java

@@ -61,9 +61,6 @@ public class JVMConfigurationKeys {
     public static final CompilerConfigurationKey<Boolean> USE_SINGLE_MODULE =
             CompilerConfigurationKey.create("combine modules for source files and binary dependencies into a single module");
 
-    public static final CompilerConfigurationKey<Boolean> SKIP_RUNTIME_VERSION_CHECK =
-            CompilerConfigurationKey.create("do not perform checks on runtime versions consistency");
-
     public static final CompilerConfigurationKey<JvmTarget> JVM_TARGET =
             CompilerConfigurationKey.create("JVM bytecode target version");