Merged requested to merge rybalkin/glib:rybalkin-gregex-jit-compilation into main
Since we ported gregex to pcre2, the JIT compiler is now available to be used. Let's undeprecate G_REGEX_OPTIMIZE flag to control whether the JIT compilation is requested, since using JIT is itself an optimization. See  for details on its implementation in pcre2.
Fixes: #566 (closed)