BUG/MINOR: ssl_ckch: Don't duplicate path when replacing a CA/CRL entry

BUG/MINOR: ssl_ckch: Don't duplicate path when replacing a CA/CRL entry

When a CA or CRL entry is replaced (via 'set ssl ca-file' or 'set ssl
crl-file' commands), the path is duplicated and used to identify the ongoing
transaction. However, if the same command is repeated, the path is still
duplicated but the transaction is not changed and the duplicated path is not
released. Thus there is a memory leak.

By reviewing the code, it appears there is no reason to duplicate the
path. It is always the filename path of the old entry. So, a reference on it
is now used. This simplifies the code and this fixes the memory leak.

This patch must be backported as far as 2.5.