Stabilize Merged jar time using date > 1980, to fix older java issues.

src/main/java/net/minecraftforge/mergetool/Merger.java

@@ -187,7 +187,7 @@ public void process() throws IOException
  private ZipEntry getNewEntry(String name)
  {
  ZipEntry ret = new ZipEntry(name);
- ret.setTime(0); //Stabilize output as java will use current time if we don't set this.
+ ret.setTime(0x92D6688800L); //Stabilize output as java will use current time if we don't set this, we can't use 0 as older java versions output different jars for values less then 1980
  return ret;
  }