qemuDomainDetachDeviceUnlink: Unlink paths in one go
qemuDomainDetachDeviceUnlink: Unlink paths in one go

Simirarly to qemuDomainAttachDeviceMknodHelper() which was
modified just a couple of commits ago, modify the unlink helper
which is called on device detach so that it can unlink multiple
files in one go instead of forking off for every single one of
them.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

nertpinx/libvirt,jardasgit/libvirt,jardasgit/libvirt,jfehlig/libvirt,crobinso/libvirt,zippy2/libvirt,nertpinx/libvirt,libvirt/libvirt,olafhering/libvirt,zippy2/libvirt,zippy2/libvirt,crobinso/libvirt,nertpinx/libvirt,olafhering/libvirt,jardasgit/libvirt,jardasgit/libvirt,olafhering/libvirt,jfehlig/libvirt,jfehlig/libvirt,crobinso/libvirt,jfehlig/libvirt,jardasgit/libvirt,crobinso/libvirt,zippy2/libvirt,libvirt/libvirt,nertpinx/libvirt,libvirt/libvirt,libvirt/libvirt,nertpinx/libvirt,olafhering/libvirt