Fix harmless LC_COLLATE[_MASK] confusion.

Fix harmless LC_COLLATE[_MASK] confusion.

Commit ca051d8b101 called newlocale(LC_COLLATE, ...) instead of
newlocale(LC_COLLATE_MASK, ...), in code reached only on FreeBSD.  They
have the same value on that OS, explaining why it worked.  Fix.

Back-patch to 14, where ca051d8b101 landed.