std.Thread: use pthread_getname_np on musl

Starting with version 1.2.3, musl now supports pthread_getname_np:
https://github.com/bminor/musl/blob/7a43f6fea9081bdd53d8a11cef9e9fab0348c53d/WHATSNEW#L2293-L2329
140ca67ea6r00ster91 committed on 2/25/2023, 11:15:46 PMparentf10100c
1 file changedLine totals unavailable