Don't report unused symbol if secondary constructor used

#KT-6997 Fixed

idea/testData/findUsages/kotlin/findClassUsages/javaClassSecondaryCtrUsages.0.kt

@@ -0,0 +1,5 @@
+// PSI_ELEMENT: org.jetbrains.kotlin.psi.JetClass
+// OPTIONS: usages, constructorUsages
+open class <caret>A {
+    constructor() {}
+}

idea/testData/findUsages/kotlin/findClassUsages/javaClassSecondaryCtrUsages.1.java

@@ -0,0 +1,5 @@
+class B {
+    public static void foo() {
+        new A()
+    }
+}

idea/testData/findUsages/kotlin/findClassUsages/javaClassSecondaryCtrUsages.results.txt

@@ -0,0 +1 @@
+New instance creation (3: 13) new A()

idea/testData/findUsages/kotlin/findClassUsages/kotlinClassSecondaryCtorUsages.0.kt

@@ -0,0 +1,5 @@
+// PSI_ELEMENT: org.jetbrains.kotlin.psi.JetClass
+// OPTIONS: usages, constructorUsages
+open class <caret>A {
+    constructor() {}
+}

idea/testData/findUsages/kotlin/findClassUsages/kotlinClassSecondaryCtorUsages.1.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    A()
+}

idea/testData/findUsages/kotlin/findClassUsages/kotlinClassSecondaryCtorUsages.results.txt

@@ -0,0 +1 @@
+New instance creation (2: 5) A()

idea/testData/inspections/unusedSymbol/class/constructorUsage.kt

@@ -0,0 +1,7 @@
+fun main(args: Array<String>) {
+    A()
+}
+
+class A {
+    constructor() {}
+}