Use plugin_author also for the InnoDB SE plugin

Move the const variable plugin_author to a common header file that is
being included by both ha_innodb.cc and i_s.cc

storage/innobase/handler/ha_innodb.cc

@@ -11367,7 +11367,7 @@ mysql_declare_plugin(innobase)
   MYSQL_STORAGE_ENGINE_PLUGIN,
   &innobase_storage_engine,
   innobase_hton_name,
-  "Innobase Oy",
+  plugin_author,
   "Supports transactions, row-level locking, and foreign keys",
   PLUGIN_LICENSE_GPL,
   innobase_init, /* Plugin Init */

storage/innobase/handler/i_s.cc

@@ -47,8 +47,6 @@ extern "C" {
 #include "trx0trx.h" /* for TRX_QUE_STATE_STR_MAX_LEN */
 }
 
-static const char plugin_author[] = "Oracle Corporation";
-
 #define OK(expr)		\
 	if ((expr) != 0) {	\
 		DBUG_RETURN(1);	\

storage/innobase/handler/i_s.h

@@ -26,6 +26,8 @@ Created July 18, 2007 Vasil Dimov
 #ifndef i_s_h
 #define i_s_h
 
+const char plugin_author[] = "Oracle Corporation";
+
 extern struct st_mysql_plugin	i_s_innodb_trx;
 extern struct st_mysql_plugin	i_s_innodb_locks;
 extern struct st_mysql_plugin	i_s_innodb_lock_waits;