Remove obsolete compiler flag -Xuse-ir

compiler/cli/cli-common/gen/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArgumentsCopyGenerated.kt

@@ -77,7 +77,6 @@ fun copyK2JVMCompilerArguments(from: K2JVMCompilerArguments, to: K2JVMCompilerAr
     to.suppressMissingBuiltinsError = from.suppressMissingBuiltinsError
     to.typeEnhancementImprovementsInStrictMode = from.typeEnhancementImprovementsInStrictMode
     to.useFastJarFileSystem = from.useFastJarFileSystem
-    to.useIR = from.useIR
     to.useJavac = from.useJavac
     to.useOldBackend = from.useOldBackend
     to.useOldClassFilesReading = from.useOldClassFilesReading

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -145,16 +145,6 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
 
     // Advanced options
 
-    @Argument(
-        value = "-Xuse-ir",
-        description = "Use the IR backend. This option has no effect unless the language version less than 1.5 is used"
-    )
-    var useIR = false
-        set(value) {
-            checkFrozen()
-            field = value
-        }
-
     @Argument(value = "-Xuse-old-backend", description = "Use the old JVM backend")
     var useOldBackend = false
         set(value) {