databases/mongodb70: fix build on 14-CURRENT

Port does not build with clang15 but does with clang14.

/usr/include/c++/v1/__algorithm/comp.h:36:71: error: invalid operands to binary expression ('const mongo::SSLX509Name::Entry' and 'const mongo::SSLX509Name::Entry')

bool operator()(const _T1& __x, const _T1& __y) const {return __x == __y;}
                                                              ~~~ ^  ~~~