runtime: x_cgo_getstackbound: initialize pthread attr
In glibc versions older than 2.32 (before commit
4721f95058),
pthread_getattr_np does not always initialize the `attr` argument,
and when it fails, it results in a NULL pointer dereference in
pthread_attr_destroy down the road.
This is the simplest way to avoid this, and an alternative to CL 585019.
Updates #65625.
Change-Id: If490fd37020b03eb084ebbdbf9ae0248916426d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/587919
Auto-Submit: Ian Lance Taylor <iant@google.com>
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Reviewed-by: Ian Lance Taylor <iant@google.com>
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