Reduce amount of redundant empty lines in C interop stubs

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/jvm/StubGenerator.kt

@@ -1388,10 +1388,13 @@ class StubGenerator(
         out("")
 
         stubs.forEach {
-            it.nativeStubLines.forEach {
+            val lines = it.nativeStubLines
-                out(it)
+            if (lines.isNotEmpty()) {
+                lines.forEach {
+                    out(it)
+                }
+                out("")
             }
-            out("")
         }
 
         if (entryPoint != null) {