qemu: Don't use `println!`

[langston-barrett]

libafl_qemu uses println!:

LibAFL/crates/libafl_qemu/src/modules/usermode/snapshot.rs

Line 242 in 70e2116

println!("mapping: {map:?}");

Expected behavior
A library should not unconditionally and directly print to the terminal.

[atharva-potdar]

can it be replaced with log::debug!("mapping: {:?}", map);?