Replace some functions with macros.

This is a non-functional change.

On a related note, the calls fil_system_enter() and fil_system_exit()
are often used in an unsafe manner. The fix of MDEV-11738 should
introduce fil_space_acquire() and remove potential race conditions.

storage/innobase/fil/fil0fil.cc

@@ -7146,27 +7146,6 @@ fil_mtr_rename_log(
 	return(err);
 }
 
-/****************************************************************//**
-Acquire fil_system mutex */
-void
-fil_system_enter(void)
-/*==================*/
-{
-	ut_ad(!mutex_own(&fil_system->mutex));
-	mutex_enter(&fil_system->mutex);
-}
-
-/****************************************************************//**
-Release fil_system mutex */
-void
-fil_system_exit(void)
-/*=================*/
-{
-	ut_ad(mutex_own(&fil_system->mutex));
-	mutex_exit(&fil_system->mutex);
-}
-
-
 /******************************************************************
 Get id of first tablespace or ULINT_UNDEFINED if none */
 UNIV_INTERN

storage/innobase/include/fil0fil.h

@@ -1290,16 +1290,10 @@ fil_space_get(
 	ulint	id);	/*!< in: space id */
 #endif /* !UNIV_INNOCHECKSUM */
 
-/****************************************************************//**
-Acquire fil_system mutex */
-void
-fil_system_enter(void);
-/*==================*/
-/****************************************************************//**
-Release fil_system mutex */
-void
-fil_system_exit(void);
-/*==================*/
+/** Acquire the fil_system mutex. */
+#define fil_system_enter()	mutex_enter(&fil_system->mutex)
+/** Release the fil_system mutex. */
+#define fil_system_exit()	mutex_exit(&fil_system->mutex)
 
 #ifndef UNIV_INNOCHECKSUM
 /*******************************************************************//**

storage/xtradb/fil/fil0fil.cc

@@ -7260,27 +7260,6 @@ fil_space_set_corrupt(
 	mutex_exit(&fil_system->mutex);
 }
 
-/****************************************************************//**
-Acquire fil_system mutex */
-void
-fil_system_enter(void)
-/*==================*/
-{
-	ut_ad(!mutex_own(&fil_system->mutex));
-	mutex_enter(&fil_system->mutex);
-}
-
-/****************************************************************//**
-Release fil_system mutex */
-void
-fil_system_exit(void)
-/*=================*/
-{
-	ut_ad(mutex_own(&fil_system->mutex));
-	mutex_exit(&fil_system->mutex);
-}
-
-
 /******************************************************************
 Get id of first tablespace or ULINT_UNDEFINED if none */
 UNIV_INTERN

storage/xtradb/include/fil0fil.h

@@ -1314,16 +1314,10 @@ fil_space_set_corrupt(
 /*==================*/
 	ulint	space_id);
 
-/****************************************************************//**
-Acquire fil_system mutex */
-void
-fil_system_enter(void);
-/*==================*/
-/****************************************************************//**
-Release fil_system mutex */
-void
-fil_system_exit(void);
-/*==================*/
+/** Acquire the fil_system mutex. */
+#define fil_system_enter()	mutex_enter(&fil_system->mutex)
+/** Release the fil_system mutex. */
+#define fil_system_exit()	mutex_exit(&fil_system->mutex)
 
 #ifndef UNIV_INNOCHECKSUM
 /*******************************************************************//**