backend: support native interop value types

also improve reliability of `==` lowering

runtime/src/main/kotlin/konan/internal/InteropBoxing.kt

@@ -0,0 +1,53 @@
+package konan.internal
+
+import kotlinx.cinterop.*
+
+class NativePtrBox(val value: NativePtr) {
+    override fun equals(other: Any?): Boolean {
+        if (other !is NativePtrBox) {
+            return false
+        }
+
+        return this.value == other.value
+    }
+
+    override fun hashCode() = value.hashCode()
+
+    override fun toString() = value.toString()
+}
+
+fun boxNativePtr(value: NativePtr) = NativePtrBox(value)
+
+class NativePointedBox(val value: NativePointed) {
+    override fun equals(other: Any?): Boolean {
+        if (other !is NativePointedBox) {
+            return false
+        }
+
+        return this.value == other.value
+    }
+
+    override fun hashCode() = value.hashCode()
+
+    override fun toString() = value.toString()
+}
+
+fun boxNativePointed(value: NativePointed?) = if (value != null) NativePointedBox(value) else null
+fun unboxNativePointed(box: NativePointedBox?) = box?.value
+
+class CPointerBox(val value: CPointer<*>) {
+    override fun equals(other: Any?): Boolean {
+        if (other !is CPointerBox) {
+            return false
+        }
+
+        return this.value == other.value
+    }
+
+    override fun hashCode() = value.hashCode()
+
+    override fun toString() = value.toString()
+}
+
+fun boxCPointer(value: CPointer<*>?) = if (value != null) CPointerBox(value) else null
+fun unboxCPointer(box: CPointerBox?) = box?.value

runtime/src/main/kotlin/konan/internal/Intrinsics.kt

@@ -1,5 +1,9 @@
 package konan.internal
 
+import kotlinx.cinterop.CPointer
+import kotlinx.cinterop.NativePointed
+import kotlinx.cinterop.NativePtr
+
 @Intrinsic external fun areEqualByValue(first: Boolean, second: Boolean): Boolean
 @Intrinsic external fun areEqualByValue(first: Char, second: Char): Boolean
 @Intrinsic external fun areEqualByValue(first: Byte, second: Byte): Boolean
@@ -9,9 +13,9 @@ package konan.internal
 @Intrinsic external fun areEqualByValue(first: Float, second: Float): Boolean
 @Intrinsic external fun areEqualByValue(first: Double, second: Double): Boolean
 
-// For comparing with `null`:
-@Intrinsic external fun areEqualByValue(first: Nothing?, second: Any?): Boolean
-@Intrinsic external fun areEqualByValue(first: Any?, second: Nothing?): Boolean
+@Intrinsic external fun areEqualByValue(first: NativePtr, second: NativePtr): Boolean
+@Intrinsic external fun areEqualByValue(first: NativePointed?, second: NativePointed?): Boolean
+@Intrinsic external fun areEqualByValue(first: CPointer<*>?, second: CPointer<*>?): Boolean
 
 inline fun areEqual(first: Any?, second: Any?): Boolean {
     return if (first == null) second == null else first.equals(second)