Address some warnings and fix JRuby test omissions

lib/net/ldap/filter.rb

@@ -490,7 +490,7 @@ def to_ber
     when :eq
       if @right == "*" # presence test
         @left.to_s.to_ber_contextspecific(7)
-      elsif @right =~ /[*]/ # substring
+      elsif @right.to_s =~ /[*]/ # substring
         # Parsing substrings is a little tricky. We use String#split to
         # break a string into substrings delimited by the * (star)
         # character. But we also need to know whether there is a star at the

test/test_ldap_connection.rb

@@ -95,7 +95,7 @@ def test_connection_refused
 
   def test_connection_timeout
     connection = Net::LDAP::Connection.new(:host => "fail.Errno::ETIMEDOUT", :port => 636, :socket_class => FakeTCPSocket)
-    stderr = capture_stderr do
+    capture_stderr do
       assert_raise Net::LDAP::Error do
         connection.socket
       end

test/test_snmp.rb

@@ -17,7 +17,7 @@ def self.raw_string(s)
   def test_invalid_packet
     data = "xxxx"
     assert_raise(Net::BER::BerError) do
-      ary = data.read_ber(Net::SNMP::AsnSyntax)
+      data.read_ber(Net::SNMP::AsnSyntax)
     end
   end
 

test/test_ssl_ber.rb

@@ -30,15 +30,13 @@ def setup
   end
 
   def test_transmit_strings
-    omit "JRuby throws an error without a real socket"
-    omit_if RUBY_PLATFORM == "java"
+    omit_if RUBY_PLATFORM == "java", "JRuby throws an error without a real socket"
 
     assert_equal "foo", transmit("foo")
   end
 
   def test_transmit_ber_encoded_numbers
-    omit "JRuby throws an error without a real socket"
-    omit_if RUBY_PLATFORM == "java"
+    omit_if RUBY_PLATFORM == "java", "JRuby throws an error without a real socket"
 
     @to.write 1234.to_ber
     assert_equal 1234, @from.read_ber