util: virprocess: Use local maximum error message size
util: virprocess: Use local maximum error message size

Use of VIR_ERROR_MAX_LENGTH is actually misleading to the readers
because it implies that the strings in virError are 1024 bytes at most.

That isn't true at least for the 'message' field as it's constructed
from concatenating the detail string which (was) max 1024 bytes with
the string variant of the error code without limiting to 1024.

Use a local copy for declaring the struct for error transport with a
comment so that's obvious that it's a local decision to use 1k buffers.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

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