Recompile all subclasses of changed classes

Previously inter-project IC recompiled only direct subclasses
of changed classes

    #KT-25455 fixed

build-common/src/org/jetbrains/kotlin/incremental/buildUtil.kt

@@ -132,6 +132,7 @@ fun ChangesCollector.getDirtyData(
 
         if (change is ChangeInfo.SignatureChanged) {
             val fqNames = if (!change.areSubclassesAffected) listOf(change.fqName) else withSubtypes(change.fqName, caches)
+            dirtyClassesFqNames.addAll(fqNames)
 
             for (classFqName in fqNames) {
                 assert(!classFqName.isRoot) { "$classFqName is root when processing $change" }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/IncrementalCompilationMultiProjectIT.kt

@@ -144,7 +144,7 @@ open class A {
 
         project.build("build") {
             assertSuccessful()
-            val affectedSources = project.projectDir.getFilesByNames("A.kt", "B.kt", "AA.kt", "BB.kt")
+            val affectedSources = project.projectDir.getFilesByNames("A.kt", "B.kt", "AA.kt", "AAA.kt", "BB.kt")
             val relativePaths = project.relativize(affectedSources)
             assertCompiledKotlinSources(relativePaths)
         }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/incrementalMultiproject/app/src/main/kotlin/foo/AA.kt

@@ -2,6 +2,6 @@ package foo
 
 import bar.*
 
-class AA : A() {
+open class AA : A() {
     fun aa() {}
 }

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/incrementalMultiproject/app/src/main/kotlin/foo/AAA.kt

@@ -5,8 +5,4 @@
 
 package foo
 
-import bar.*
-
-class AAA : A() {
-    fun aa() {}
-}
+class AAA : AA()