VMS: fix collected error strings

It turns out that on VMS, strerror() returns messages with added
spaces at the end.

We wouldn't had noticed if it wasn't for perl trimming those spaces
off for its own sake and thereby having test/recipes/02-test_errstr.t
fail on VMS.

The safe fix is to do the same trimming ourselves.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7701)