sljit, the JIT in pcre2, doesn't quite fully work on windows on
arm yet (although the subset of functionality used by pcre2 might
mostly work). On arm64, it fails to compile (although working around
that failure is pretty easy), when using clang in MinGW mode
(where __GNUC__ is defined, making the JIT auto-enabled).

Disable it in these configurations until it has been fully tested
and fixed upstream first.

Change-Id: Ie9681cb7cdd1960586ba194c71e057eb918cb419
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>