Added HandlerSocket plugin

- Fixed compiler errors
- Modified Makefiles to be part of plugin directory
- Some minor changes in database.cpp to use the new MariaDB handler interface

plugin/handler_socket/perl-Net-HandlerSocket/Makefile.PL.installed

@@ -0,0 +1,20 @@
+# use 5.010000;
+use ExtUtils::MakeMaker;
+# See lib/ExtUtils/MakeMaker.pm for details of how to influence
+# the contents of the Makefile that is written.
+WriteMakefile(
+    NAME              => 'Net::HandlerSocket',
+    VERSION_FROM      => 'lib/Net/HandlerSocket.pm', # finds $VERSION
+    PREREQ_PM         => {}, # e.g., Module::Name => 1.1
+    ($] >= 5.005 ?     ## Add these new keywords supported since 5.005
+      (ABSTRACT_FROM  => 'lib/Net/HandlerSocket.pm', # retrieve abstract from module
+       AUTHOR         => 'higuchi dot akira at dena dot jp>') : ()),
+    CC                => 'g++ -fPIC',
+    LD                => 'g++ -fPIC',
+    LIBS              => ['-lhsclient'], # e.g., '-lm'
+    DEFINE            => '', # e.g., '-DHAVE_SOMETHING'
+    INC               => '-I. -I/usr/include/handlersocket',
+    OPTIMIZE          => '-g -O3 -Wall -Wno-unused',
+	# Un-comment this if you add C files to link with later:
+    # OBJECT            => '$(O_FILES)', # link all the C files too
+);