[K/N][IR] Used .isFakeOverride instead of a special origin

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/SymbolTable.kt

@@ -745,7 +745,8 @@ class SymbolTable(
                 isLateinit = descriptor.isLateInit,
                 isDelegated = isDelegated,
                 isExternal = descriptor.isEffectivelyExternal(),
-                isExpect = descriptor.isExpect
+                isExpect = descriptor.isExpect,
+                isFakeOverride = descriptor.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE
             ).apply {
                 metadata = DescriptorMetadataSource.Property(symbol.descriptor)
             }

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/overrides.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.ir.util
 
+import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.DescriptorMetadataSource
@@ -24,7 +25,17 @@ fun SymbolTable.declareSimpleFunctionWithOverrides(
         with(descriptor) {
             irFactory.createFunction(
                 startOffset, endOffset, origin, it, nameProvider.nameForDeclaration(this),
-                visibility, modality, IrUninitializedType, isInline, isEffectivelyExternal(), isTailrec, isSuspend, isOperator, isInfix, isExpect
+                visibility,
+                modality,
+                IrUninitializedType,
+                isInline,
+                isEffectivelyExternal(),
+                isTailrec,
+                isSuspend,
+                isOperator,
+                isInfix,
+                isExpect,
+                isFakeOverride = descriptor.kind == CallableMemberDescriptor.Kind.FAKE_OVERRIDE
             ).also { declaration ->
                 declaration.metadata = DescriptorMetadataSource.Function(this)
             }