ACPICA: actbl1: Replace 1-element arrays with flexible arrays

ACPICA: actbl1: Replace 1-element arrays with flexible arrays

ACPICA commit 8c9bd5d151f77767b2fd937911848b7159dc8ee9

Similar to "Replace one-element array with flexible-array", replace the
1-element array with a proper flexible array member as defined by C99.

This allows the code to operate without tripping compile-time and run-
time bounds checkers (e.g. via __builtin_object_size(), -fsanitize=bounds,
and/or -fstrict-flex-arrays=3).

No .text nor .data differences result from this change.

Link: https://github.com/acpica/acpica/commit/8c9bd5d1
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>