Add information about secondary constructors to synthetic classes.

Before this, descriptors for such constructors were created in-place where they needed by the codegens.
However, presence of symbol table in IR backend requires the single instance of constructor descriptor across all compilation to be able to reference it and create a symbol. This support of generics in kotlinx.serialization on Kotlin/Native.

compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java

@@ -37,6 +37,7 @@ import org.jetbrains.kotlin.name.ClassId;
 import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.psi.*;
+import org.jetbrains.kotlin.psi.synthetics.SyntheticClassOrObjectDescriptor;
 import org.jetbrains.kotlin.resolve.*;
 import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilKt;
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
@@ -441,7 +442,8 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         try {
             lookupConstructorExpressionsInClosureIfPresent();
             constructorCodegen.generatePrimaryConstructor(delegationFieldsInfo, superClassAsmType);
-            if (!descriptor.isInline()) {
+            if (!descriptor.isInline() && !(descriptor instanceof SyntheticClassOrObjectDescriptor)) {
+                // Synthetic classes does not have declarations for secondary constructors
                 for (ClassConstructorDescriptor secondaryConstructor : DescriptorUtilsKt.getSecondaryConstructors(descriptor)) {
                     constructorCodegen.generateSecondaryConstructor(secondaryConstructor, superClassAsmType);
                 }