[Eva] use callsite for populate_funspec locations

tests/impact/oracle/call.2.res.oracle

tests/impact/oracle/undef_function.res.oracle

tests/impact/oracle/variadic.res.oracle

tests/libc/oracle/search_h.res.oracle

tests/libc/oracle/spawn_h.res.oracle

tests/pdg/oracle/bts1194.res.oracle

tests/pdg/oracle/no_body.res.oracle

tests/pdg/oracle/pb_infinite_loop.2.res.oracle

tests/pdg/oracle/variadic.res.oracle

tests/scope/oracle/bts383.res.oracle

tests/slicing/oracle/bts1768.res.oracle

tests/slicing/oracle/bts709.res.oracle

tests/slicing/oracle/combine.res.oracle

tests/slicing/oracle/filter.res.oracle

tests/slicing/oracle/loops.15.res.oracle

tests/slicing/oracle/loops.16.res.oracle

tests/slicing/oracle/loops.17.res.oracle

tests/slicing/oracle/loops.18.res.oracle

tests/slicing/oracle/min_call.res.oracle

tests/slicing/oracle/ptr_fct.res.oracle