Fix error transformation on older Rubies

contrib/ruby/lib/trilogy.rb

@@ -8,6 +8,14 @@
 require "trilogy/encoding"
 
 class Trilogy
+  IO_TIMEOUT_ERROR =
+    if defined?(IO::TimeoutError)
+      IO::TimeoutError
+    else
+      Class.new
+    end
+  private_constant :IO_TIMEOUT_ERROR
+
   def initialize(options = {})
     options[:port] = options[:port].to_i if options[:port]
     mysql_encoding = options[:encoding] || "utf8mb4"
@@ -47,9 +55,9 @@ def initialize(options = {})
         path = options[:socket] ||= "/tmp/mysql.sock"
         socket = UNIXSocket.new(path)
       end
-    rescue IO::TimeoutError => e
+    rescue Errno::ETIMEDOUT, IO_TIMEOUT_ERROR => e
       raise Trilogy::TimeoutError, e.message
-    rescue Socket::ResolutionError => e
+    rescue SocketError => e
       connection_str = host ? "#{host}:#{port}" : path
       raise Trilogy::BaseConnectionError, "unable to connect to \"#{connection_str}\": #{e.message}"
     rescue => e