libvmm: use a const char pointer for vm name in struct vmctx

[rew]

Summary

Allow callers of vm_get_name() to retrieve the vm name without having to
allocate a buffer.

[jhb]

lib/libvmmapi/vmmapi.c

499–500

Note that you could just change this function and still leave 'ctx->name' as char * so you don't have to change around the code around the strcpy in vm_open.

usr.sbin/bhyve/snapshot.c

1129

I would maybe just axe the vmname_buf variable entirely (it's a bit odd now as it's a pointer rather than a buffer) and just inline the function call here.

1520–1521

Similarly.

usr.sbin/bhyvectl/bhyvectl.c

1691 ↗

(On Diff #102813)

It seems a bit odd that this even takes the ctx as an arg btw rather than just passing through the string from the --vm argument directly?

[rew]

updated per feedback from jhb

[rew]

I split out the bhyvectl changes into a separate review:

https://reviews.freebsd.org/D34399