Fix extra reference of parameters of rrd_fetch_dbi_{long,double} (#1255)

Fix extra reference of parameters of rrd_fetch_dbi_{long,double} (#1255)

Functions rrd_fetch_dbi_long and rrd_fetch_dbi_double currently take
the first parameter of type "bi_result result *" even though that is
already a pointer and the use of that parameter suggests the extra
indirection is not wanted.  What is more, the caller passes just
"bi_result result" to the corresponding actual arguments which results
in compile errors with GCC 14 because it now does not accept
incompatible pointer types by default.