Don't use the '-' character in class names for synthetics

This is to work around https://issuetracker.google.com/178805864
until lint updates have landed everywhere.

Change-Id: I4365700d7e458308096339442ae950fc9ed5a9e0

src/main/java/com/android/tools/r8/synthesis/SyntheticNaming.java

diff --git a/src/main/java/com/android/tools/r8/synthesis/SyntheticNaming.java b/src/main/java/com/android/tools/r8/synthesis/SyntheticNaming.java
index 25e59ae..1b80f41 100644
--- a/src/main/java/com/android/tools/r8/synthesis/SyntheticNaming.java
+++ b/src/main/java/com/android/tools/r8/synthesis/SyntheticNaming.java
@@ -63,7 +63,7 @@
     }
   }
 
-  private static final String SYNTHETIC_CLASS_SEPARATOR = "-$$";
+  private static final String SYNTHETIC_CLASS_SEPARATOR = "$$";
   /**
    * The internal synthetic class separator is only used for representing synthetic items during
    * compilation. In particular, this separator must never be used to write synthetic classes to the

src/test/examplesAndroidO/multidex004/ref-list-1.txt

diff --git a/src/test/examplesAndroidO/multidex004/ref-list-1.txt b/src/test/examplesAndroidO/multidex004/ref-list-1.txt
index c817c33..bd195b3 100644
--- a/src/test/examplesAndroidO/multidex004/ref-list-1.txt
+++ b/src/test/examplesAndroidO/multidex004/ref-list-1.txt
@@ -1,4 +1,4 @@
-Lmultidex004/MainActivity-$$ExternalSyntheticLambda0;
+Lmultidex004/MainActivity$$ExternalSyntheticLambda0;
 Lmultidex004/MainActivity;
 Lmultidex004/VersionInterface;
 Lmultidex004/VersionStatic;