Merge 10.6 into 10.10

The MDEV-29693 conflict resolution is from Monty, as well as is
a bug fix where ANALYZE TABLE wrongly built histograms for
single-column PRIMARY KEY.
Also includes a fix for safe_malloc error reporting.

Other things:
- Copied main.log_slow from 10.4 to avoid mtr issue

Disabled test:
- spider/bugfix.mdev_27239 because we started to get
  +Error	1429 Unable to connect to foreign data source: localhost
  -Error	1158 Got an error reading communication packets
- main.delayed
  - Bug#54332 Deadlock with two connections doing LOCK TABLE+INSERT DELAYED
    This part is disabled for now as it fails randomly with different
    warnings/errors (no corruption).

mysql-test/main/innodb_ext_key,off.rdiff

@@ -1,5 +1,5 @@
---- innodb_ext_key.result
-+++ innodb_ext_key,off.result
+--- main/innodb_ext_key.result
++++ main/innodb_ext_key,off.reject
 @@ -9,7 +9,7 @@
  explain
  select count(*) from lineitem where l_orderkey=130 and l_shipdate='1992-07-01';
@@ -230,14 +230,14 @@
  Handler_read_retry	0
  Handler_read_rnd	0
 @@ -314,8 +314,8 @@
- select * from t0, part ignore index (primary)
+ select straight_join * from t0, part ignore index (primary)
  where p_partkey=t0.a and p_size=1;
  id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 -1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	5	Using where
 -1	SIMPLE	part	eq_ref	i_p_size	i_p_size	9	const,dbt3_s001.t0.a	1	
 +1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	5	
 +1	SIMPLE	part	ref	i_p_size	i_p_size	5	const	5	Using index condition
- select * from t0,  part ignore index (primary)
+ select straight_join * from t0,  part ignore index (primary)
  where p_partkey=t0.a and p_size=1;
  a	p_partkey	p_name	p_mfgr	p_brand	p_type	p_size	p_container	p_retailprice	p_comment
 @@ -494,7 +494,7 @@