MDEV-19629 post-merge fixes

* it isn't "pfs" function, don't call it Item_func_pfs,
  don't use item_pfsfunc.*
* tests don't depend on performance schema, put in the main suite
* inherit from Item_str_ascii_func
* use connection collation, not utf8mb3_general_ci
* set result length in fix_length_and_dec
* do not set maybe_null
* use my_snprintf() where possible
* don't set m_value.ptr on every invocation
* update sys schema to use the format_pico_time()
* len must be size_t (compilation error on Windows)
* the correct function name for double->double is fabs()
* drop volatile hack

Author: vuvova

libmysqld/CMakeLists.txt

@@ -64,7 +64,7 @@ SET(SQL_EMBEDDED_SOURCES emb_qcache.cc libmysqld.c lib_sql.cc
            ../sql/item.cc ../sql/item_create.cc ../sql/item_func.cc 
            ../sql/item_geofunc.cc ../sql/item_row.cc ../sql/item_strfunc.cc 
            ../sql/item_subselect.cc ../sql/item_sum.cc ../sql/item_timefunc.cc 
-           ../sql/item_xmlfunc.cc ../sql/item_jsonfunc.cc ../sql/item_pfsfunc.cc
+           ../sql/item_xmlfunc.cc ../sql/item_jsonfunc.cc
            ../sql/key.cc ../sql/lock.cc ../sql/log.cc 
            ../sql/log_event.cc ../sql/log_event_server.cc 
            ../sql/mf_iocache.cc ../sql/my_decimal.cc 

mysql-test/suite/perfschema/r/pfs_functions.result renamed to mysql-test/main/func_format.result

@@ -2,11 +2,11 @@ DESC sys.host_summary;
 Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 statements	decimal(64,0)	YES		NULL	
-statement_latency	text	YES		NULL	
-statement_avg_latency	text	YES		NULL	
+statement_latency	varchar(12)	YES		NULL	
+statement_avg_latency	varchar(12)	YES		NULL	
 table_scans	decimal(65,0)	YES		NULL	
 file_ios	decimal(64,0)	YES		NULL	
-file_io_latency	text	YES		NULL	
+file_io_latency	varchar(12)	YES		NULL	
 current_connections	decimal(41,0)	YES		NULL	
 total_connections	decimal(41,0)	YES		NULL	
 unique_users	bigint(21)	NO		0	

mysql-test/suite/perfschema/t/pfs_functions.test renamed to mysql-test/main/func_format.test

@@ -2,7 +2,7 @@ DESC sys.host_summary_by_file_io;
 Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 ios	decimal(42,0)	YES		NULL	
-io_latency	text	YES		NULL	
+io_latency	varchar(12)	YES		NULL	
 SELECT * FROM sys.host_summary_by_file_io;
 DESC sys.x$host_summary_by_file_io;
 Field	Type	Null	Key	Default	Extra

mysql-test/suite/sysschema/r/v_host_summary.result

@@ -3,8 +3,8 @@ Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 event_name	varchar(128)	NO		NULL	
 total	bigint(20) unsigned	NO		NULL	
-total_latency	text	YES		NULL	
-max_latency	text	YES		NULL	
+total_latency	varchar(12)	YES		NULL	
+max_latency	varchar(12)	YES		NULL	
 SELECT * FROM sys.host_summary_by_file_io_type;
 DESC sys.x$host_summary_by_file_io_type;
 Field	Type	Null	Key	Default	Extra

mysql-test/suite/sysschema/r/v_host_summary_by_file_io.result

@@ -3,8 +3,8 @@ Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 event_name	varchar(128)	NO		NULL	
 total	bigint(20) unsigned	NO		NULL	
-total_latency	text	YES		NULL	
-avg_latency	text	YES		NULL	
+total_latency	varchar(12)	YES		NULL	
+avg_latency	varchar(12)	YES		NULL	
 SELECT * FROM sys.host_summary_by_stages;
 DESC sys.x$host_summary_by_stages;
 Field	Type	Null	Key	Default	Extra

mysql-test/suite/sysschema/r/v_host_summary_by_file_io_type.result

@@ -2,9 +2,9 @@ DESC sys.host_summary_by_statement_latency;
 Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 total	decimal(42,0)	YES		NULL	
-total_latency	text	YES		NULL	
-max_latency	text	YES		NULL	
-lock_latency	text	YES		NULL	
+total_latency	varchar(12)	YES		NULL	
+max_latency	varchar(12)	YES		NULL	
+lock_latency	varchar(12)	YES		NULL	
 rows_sent	decimal(42,0)	YES		NULL	
 rows_examined	decimal(42,0)	YES		NULL	
 rows_affected	decimal(42,0)	YES		NULL	

mysql-test/suite/sysschema/r/v_host_summary_by_stages.result

@@ -3,9 +3,9 @@ Field	Type	Null	Key	Default	Extra
 host	varchar(255)	YES		NULL	
 statement	varchar(128)	YES		NULL	
 total	bigint(20) unsigned	NO		NULL	
-total_latency	text	YES		NULL	
-max_latency	text	YES		NULL	
-lock_latency	text	YES		NULL	
+total_latency	varchar(12)	YES		NULL	
+max_latency	varchar(12)	YES		NULL	
+lock_latency	varchar(12)	YES		NULL	
 rows_sent	bigint(20) unsigned	NO		NULL	
 rows_examined	bigint(20) unsigned	NO		NULL	
 rows_affected	bigint(20) unsigned	NO		NULL	

mysql-test/suite/sysschema/r/v_host_summary_by_statement_latency.result

@@ -2,10 +2,10 @@ DESC sys.io_by_thread_by_latency;
 Field	Type	Null	Key	Default	Extra
 user	varchar(384)	YES		NULL	
 total	decimal(42,0)	YES		NULL	
-total_latency	text	YES		NULL	
-min_latency	text	YES		NULL	
-avg_latency	text	YES		NULL	
-max_latency	text	YES		NULL	
+total_latency	varchar(12)	YES		NULL	
+min_latency	varchar(12)	YES		NULL	
+avg_latency	varchar(12)	YES		NULL	
+max_latency	varchar(12)	YES		NULL	
 thread_id	bigint(20) unsigned	NO		NULL	
 processlist_id	bigint(20) unsigned	YES		NULL	
 SELECT * FROM sys.io_by_thread_by_latency;