get rid off Java 6 checks in code - as the min requirement is 7

Author: kares

src/main/java/org/jruby/ext/openssl/OpenSSL.java

@@ -251,11 +251,6 @@ public static String javaVersion(final String def) {
         return javaVersionProperty;
     }
 
-    static boolean javaVersion6(final boolean atLeast) {
-        final int gt = new Version("1.6").compareTo(new Version(javaVersion("0.0")));
-        return atLeast ? gt <= 0 : gt == 0;
-    }
-
     static boolean javaVersion7(final boolean atLeast) {
         final int gt = new Version("1.7").compareTo(new Version(javaVersion("0.0")));
         return atLeast ? gt <= 0 : gt == 0;
@@ -272,7 +267,7 @@ static boolean javaVersion9(final boolean atLeast) {
     }
 
     private static String javaName(final String def) {
-        // Sun Java 6 or Oracle Java 7/8
+        // Sun Java 6 or Oracle Java 7/8/9/10
         // "Java HotSpot(TM) Server VM" or "Java HotSpot(TM) 64-Bit Server VM"
         // OpenJDK :
         // "OpenJDK 64-Bit Server VM"

src/main/java/org/jruby/ext/openssl/Random.java

@@ -56,12 +56,6 @@ private static Holder createHolderImpl() {
         if (HOLDER_TYPE.equals("default") || HOLDER_TYPE.equals("thread-local")) {
             return new ThreadLocalHolder();
         }
-        if (HOLDER_TYPE.equals("")) {
-            // NOTE: fine to remove when support for running on Java 6 is gone ...
-            if (OpenSSL.javaVersion6(false)) {
-                return new SharedHolder(); // can not-use ThreadLocalRandom.current()
-            }
-        }
         if (HOLDER_TYPE.equals("shared")) {
             return new SharedHolder();
         }