Exported `pthread_attr_get_np` under `_DEFAULT_SOURCE`. Otherwise,
the presence of this function in `libroot.so` without a definition
would confuse some configuration scripts.
Change-Id: I623ebefc98800e9528dc48859c2aefc828821f27
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6383
Reviewed-by: Jessica Hamilton <[email protected]>
Tested-by: Commit checker robot <[email protected]>
Trung Nguyen
f967e2c0c7