Fix CMakeLists.txt for cmake Ninja generator
remove HTON_FLUSH_AFTER_RENAME (BDB-ism, unused for years)
MDEV-4260 Don't create frm files for temporary tables

* Don't write frm for tmp tables
* pass frm image down to open_table_uncached, when possible
* don't use truncate-by-recreate for temp tables - cannot recreate
  without frm, and delete_all_rows is faster anyway
main.temp_table_frm failure on fulltest (--embedded, when TMPDIR=/tmp)

use more restrictive --list_files to hide the usual /tmp garbage
remove unused sql/examples
cmake: prefer INSTALL(PROGRAMS over INSTALL(FILES
cmake cleanup: use MY_CHECK_AND_SET_COMPILER_FLAG.

move MY_CHECK_C_COMPILER_FLAG and MY_CHECK_CXX_COMPILER_FLAG
to a separate file, introduce MY_CHECK_AND_SET_COMPILER_FLAG,
use it where possible.
MDEV-5730 enhance security using special compilation options

-Wl,-z,relro,-z,now
-pie
-fstack-protector --param=ssp-buffer-size=4
-D_FORTIFY_SOURCE=2