MDEV-14533 Provide information_schema tables using which hardware

information can be obtained.

plugin only enabled for Linux, as it fails building on BSD/MacOSX.
disks.test fixed.

plugin/disks/CMakeLists.txt

-IF(NOT WIN32)
+IF("${CMAKE_SYSTEM}" MATCHES "Linux")
   INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/sql)
   MYSQL_ADD_PLUGIN(DISKS information_schema_disks.cc MODULE_ONLY RECOMPILE_FOR_EMBEDDED)
 ENDIF()

plugin/disks/mysql-test/disks/disks.result

-install plugin DISKS soname 'disks';
 show create table information_schema.disks;
 Table	Create Table
 DISKS	CREATE TEMPORARY TABLE `DISKS` (
@@ -11,4 +10,3 @@ DISKS	CREATE TEMPORARY TABLE `DISKS` (
 select sum(Total) > sum(Available), sum(Total)>sum(Used) from information_schema.disks;
 sum(Total) > sum(Available)	sum(Total)>sum(Used)
 1	1
-uninstall plugin DISKS;

plugin/disks/mysql-test/disks/disks.test

---source include/not_windows.inc
-
-if (!$DISKS_SO) {
-  skip No DISKS plugin;
-}
-
-install plugin DISKS soname 'disks';
 show create table information_schema.disks;
 select sum(Total) > sum(Available), sum(Total)>sum(Used) from information_schema.disks;
-
-uninstall plugin DISKS;