[vcs-log] remove unused InMemoryMap

Was introduced in d401d0d for usage in log indexes when persistence map could not be created for some reason.
Stopped being used in 32e141e: when phm can not be created then indexes could not be created.

platform/vcs-log/impl/src/com/intellij/vcs/log/data/InMemoryMap.java

@@ -1,69 +0,0 @@
-/*
- * Copyright 2000-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.intellij.vcs.log.data;
-
-import com.intellij.util.Processor;
-import com.intellij.util.io.PersistentMap;
-
-import java.io.IOException;
-import java.util.HashMap;
-import java.util.Map;
-
-public class InMemoryMap<K, V> implements PersistentMap<K, V> {
-  private final Map<K, V> myMap = new HashMap<>();
-
-  @Override
-  public V get(K key) throws IOException {
-    return myMap.get(key);
-  }
-
-  @Override
-  public void put(K key, V value) throws IOException {
-    myMap.put(key, value);
-  }
-
-  @Override
-  public boolean processKeys(Processor<K> processor) throws IOException {
-    for (K key : myMap.keySet()) {
-      if (!processor.process(key)) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  @Override
-  public boolean isClosed() {
-    return false;
-  }
-
-  @Override
-  public boolean isDirty() {
-    return false;
-  }
-
-  @Override
-  public void force() {
-  }
-
-  @Override
-  public void close() throws IOException {
-  }
-
-  @Override
-  public void markDirty() throws IOException {
-  }
-}