[MDEV-12618] mysys/mysys_priv.h shouldn't use O_EXEC as O_PATH on illumos - Jira

In mysys_priv.h MariaDB defines:

#if !defined(O_PATH) && defined(O_EXEC) /* FreeBSD */

#define O_PATH O_EXEC

#endif

This makes mariadb server trying to do:

	openat64(-1, "/var", O_EXEC|O_NOFOLLOW)		Err#8 ENOEXEC

which errors out.
Solaris uses POSIX O_SEARCH for this. The following would work:

#if !defined(O_PATH)

#if defined(O_SEARCH)  /* illumos */

#define O_PATH O_SEARCH

#elif defined(O_EXEC) /* FreeBSD */

#define O_PATH O_EXEC

#endif

#endif

Or better switch to using O_SEARCH (as it's posix-compliant ) and defining it on systems which don't have it.

is duplicated by

MDEV-12310 openat(<directory>, ...O_EXEC) fails on Illumos / Solaris.