Fix java8 compatibility (#390)

* ByteBuffer.limit() compiled with JDK9+ shows  java.lang.NoSuchMethodError: java.nio.ByteBuffer.limit(I)Ljava/nio/ByteBuffer; error in JDK8
* Set --release 8 JDK option
* Do not use --release 8 option in JDK8

build.sbt

@@ -27,7 +27,14 @@ ThisBuild / dynverSeparator := "-"
 ThisBuild / scalaVersion := "2.12.11"
 
 // For building jars for JDK8
-ThisBuild / javacOptions ++= Seq("-source", "1.8", "-target", "1.8")
+ThisBuild / javacOptions ++= {
+  if (scala.util.Properties.isJavaAtLeast("9")) {
+    // --release 8 option is not available in JDK8
+    Seq("--release", "8")
+  } else {
+    Seq.empty
+  }
+}
 Compile / compile / javacOptions ++= Seq("-encoding", "UTF-8", "-Xlint:unchecked", "-Xlint:deprecation")
 
 doc / javacOptions := {

src/main/java/org/xerial/snappy/Snappy.java

@@ -28,6 +28,7 @@
 import java.io.InputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.URL;
+import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.util.Properties;
@@ -154,7 +155,7 @@ public static int compress(ByteBuffer uncompressed, ByteBuffer compressed)
 
         //         pos  limit
         // [ ......BBBBBBB.........]
-        compressed.limit(cPos + compressedSize);
+        ((Buffer) compressed).limit(cPos + compressedSize);
 
         return compressedSize;
     }