Don't compute SSLContext over and over again, port e8d7662 to master

Author: Stephane Landelle

api/src/main/java/org/asynchttpclient/util/SslUtils.java

@@ -35,6 +35,8 @@
  */
 public class SslUtils {
 
+	private static SSLContext context = null;
+
     public static SSLEngine getSSLEngine()
             throws GeneralSecurityException, IOException {
         SSLEngine engine = null;
@@ -50,12 +52,16 @@ public static SSLEngine getSSLEngine()
 
     public static SSLContext getSSLContext()
             throws GeneralSecurityException, IOException {
-        SSLConfig config = new SSLConfig();
-        if (config.keyStoreLocation == null || config.trustStoreLocation == null) {
-            return getLooseSSLContext();
-        } else {
-            return getStrictSSLContext(config);
-        }
+    	if (context == null) {
+            SSLConfig config = new SSLConfig();
+            if (config.keyStoreLocation == null
+                    || config.trustStoreLocation == null) {
+                context = getLooseSSLContext();
+            } else {
+                context = getStrictSSLContext(config);
+            }
+    	}
+    	return context;
     }
 
     static SSLContext getStrictSSLContext(SSLConfig config)