Don't make unused constructors abstract

Fixes: 203495782
Change-Id: Iec2a89276c27d7ffbec9022caf1006d102eb8cf3

src/main/java/com/android/tools/r8/graph/ProgramMethod.java

diff --git a/src/main/java/com/android/tools/r8/graph/ProgramMethod.java b/src/main/java/com/android/tools/r8/graph/ProgramMethod.java
index 98c8bd2..146e33f 100644
--- a/src/main/java/com/android/tools/r8/graph/ProgramMethod.java
+++ b/src/main/java/com/android/tools/r8/graph/ProgramMethod.java
@@ -78,6 +78,7 @@
         && !getAccessFlags().isNative()
         && !getAccessFlags().isPrivate()
         && !getAccessFlags().isStatic()
+        && !getDefinition().isInstanceInitializer()
         && !appView.appInfo().isFailedResolutionTarget(getReference());
   }