MDEV-8192 - THD::set_command() takes 0.05% in OLTP RO

Moved THD::set_command() definition to sql_class.h so that it can be inlined.

Overhead change:
THD::set_command        0.05% -> out of radar

sql/sql_class.cc

@@ -5056,14 +5056,6 @@ void THD::set_status_no_good_index_used()
 #endif
 }
 
-void THD::set_command(enum enum_server_command command)
-{
-  m_command= command;
-#ifdef HAVE_PSI_THREAD_INTERFACE
-  PSI_STATEMENT_CALL(set_thread_command)(m_command);
-#endif
-}
-
 /** Assign a new value to thd->query and thd->query_id.  */
 
 void THD::set_query_and_id(char *query_arg, uint32 query_length_arg,

sql/sql_class.h

@@ -3687,7 +3687,13 @@ private:
 public:
   /** Overloaded to guard query/query_length fields */
   virtual void set_statement(Statement *stmt);
-  void set_command(enum enum_server_command command);
+  void set_command(enum enum_server_command command)
+  {
+    m_command= command;
+#ifdef HAVE_PSI_THREAD_INTERFACE
+    PSI_STATEMENT_CALL(set_thread_command)(m_command);
+#endif
+  }
   inline enum enum_server_command get_command() const
   { return m_command; }