qemuDomainNamespaceMknodPaths: Create more files in one go

qemuDomainNamespaceMknodPaths: Create more files in one go

While the previous commit prepared the helper function run in a
forked off helper (with corresponding struct), this commit
modifies the caller, which now create all files requested in a
single process and does not fork off for every single path.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>