This file was imported from glibx and uses __USE_GNU as defined by
glibc(s features.h. Our implementation of features.h is simpler, just
defining _DEFAULT_SOURCE directly and that's what we use in other
headers.
As a result, using GNU extensions to regex.h required defining __USE_GNU
directly in applications (for example in TraX).
Fixes #11818
Change-Id: I11e4cf2e88c330cf58083852c4b33aedb8a3a9ea
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7238
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
dbe86e4638