remove redundant tests from mysql-test/include/*.inc files

Some tests are skipped by checks in suite.pm. It is redundant to
have an sql-level run-time check in the .inc file itself.

In some cases it's not only redundant, but dangerous.
After one bug in 10.2 innodb.create_isl_with_direct failed
to start InnoDB, but the server started fine (just without InnoDB)
and instead of failing, the test was skipped by run-time check in
have_innodb.inc.

# Conflicts:
#	mysql-test/include/not_embedded.inc
#	mysql-test/r/change_user_notembedded.result
#	mysql-test/suite.pm
#	mysql-test/t/change_user_notembedded.test

mysql-test/include/have_debug.inc

@@ -2,8 +2,3 @@
 # suite.pm will make sure that all tests including this file
 # will be skipped unless this is a debug build.
 #
-# The test below is redundant
-
-if (`select version() not like '%debug%'`) {
-  --skip Needs a debug build
-}

mysql-test/include/have_example_plugin.inc

@@ -1,14 +1,4 @@
 #
-# Check if server has support for loading plugins
+# suite.pm will make sure that all tests including this file
+# will be skipped unless dynamic ha_example plugin is available
 #
-if (`SELECT @@have_dynamic_loading != 'YES'`) {
-  --skip Example plugin requires dynamic loading
-}
-
-#
-# Check if the variable EXAMPLE_PLUGIN is set
-#
-if (!$HA_EXAMPLE_SO) {
-  --skip Need example plugin
-}
-

mysql-test/include/have_innodb.inc

@@ -2,9 +2,3 @@
 # suite.pm will make sure that all tests including this file
 # will be skipped unless innodb or xtradb is enabled
 #
-# The test below is redundant
-
-if (`SELECT COUNT(*) = 0 FROM INFORMATION_SCHEMA.ENGINES WHERE engine = 'innodb' AND support IN ('YES', 'DEFAULT', 'ENABLED')`)
-{
-  --skip Test requires InnoDB.
-}

mysql-test/include/have_xtradb.inc

@@ -2,10 +2,3 @@
 # suite.pm will make sure that all tests including this file
 # will be skipped unless xtradb is enabled
 #
-# The test below is redundant
-
-if (!`SELECT count(*) FROM information_schema.plugins WHERE
-      plugin_name = 'innodb' AND plugin_status = 'active' AND
-      plugin_description LIKE '%xtradb%'`){
-  skip Needs XtraDB engine;
-}

mysql-test/include/not_embedded.inc

@@ -2,9 +2,3 @@
 # suite.pm will make sure that all tests including this file
 # will be skipped unless this is an embedded test run
 #
-# The test below is redundant
-
-if (`select version() like '%embedded%'`) {
-  This should never happen;
-}
-

mysql-test/include/not_windows.inc

@@ -1,4 +1,4 @@
---require r/not_windows.require
-disable_query_log;
-select convert(@@version_compile_os using latin1) NOT IN ("Win32","Win64","Windows") as "TRUE";
-enable_query_log;
+#
+# suite.pm will make sure that all tests including this file
+# will be skipped unless this is on Windows
+#

mysql-test/r/not_windows.require

@@ -1,2 +0,0 @@
-TRUE
-1