lookup_name_info always copies the name that is passed in. However,
normally a copy is not needed. This patch changes this class to avoid
copying. This required changing the "name" method to return something
else; I chose a gdb::string_view, to avoid excessive calls to strlen
in the code using the lookup_name_info. However, as this class does
not allow an arbitrary string_view, I've also added a c_str method
that guarantees a \0-terminated result -- a pedantic difference but
one that respects the string_view contract, IMO.
gdb/ChangeLog
2020-04-01 Tom Tromey <tromey@adacore.com>