Todo: Add support `info proc mappings` for qemu-user 8.1

[bata24]

I have built qemu 8.1.2 from source. but info proc mappings under qemu-x86_64 is fail, why? All of other architecture (e.g.: qemu-aarch64, qemu-arm, qemu-sh4, qemu-i386, ...) are okay.

gef> version 
------------------------------------------------------------------------------ versions ------------------------------------------------------------------------------
OS:                     Ubuntu 23.04
...
qemu:                   qemu-x86_64 version 8.1.2
...
gef> info proc mappings
Not supported on this target.
gef> 

[bata24]

Supported if available.