stubs: split record/replay stubs further

stubs: split record/replay stubs further

replay.c symbols are only needed by user mode emulation, with the
exception of replay_mode that is needed by both user mode emulation
(by way of qemu_guest_getrandom) and block layer tools (by way of
util/qemu-timer.c).

Since it is needed by libqemuutil rather than specific files that
are part of the tools and emulators, split the replay_mode stub
into its own file.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240408155330.522792-17-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>