[FIX] project_issue: number of issues for a customer
[FIX] project_issue: number of issues for a customer

When counting the number of issues for a customer, all the the contacts
of this customer must be taken into account.

opw:676985

ygol/odoo,laslabs/odoo,dfang/odoo,bplancher/odoo,storm-computers/odoo,laslabs/odoo,bplancher/odoo,ygol/odoo,dfang/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,dfang/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,dfang/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,hip-odoo/odoo,dfang/odoo,microcom/odoo,storm-computers/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,ygol/odoo,bplancher/odoo,laslabs/odoo,bplancher/odoo,hip-odoo/odoo,laslabs/odoo,bplancher/odoo,hip-odoo/odoo,hip-odoo/odoo,Elico-Corp/odoo_OCB,microcom/odoo,microcom/odoo,microcom/odoo,dfang/odoo,microcom/odoo,bplancher/odoo,ygol/odoo,laslabs/odoo,ygol/odoo,ygol/odoo,storm-computers/odoo,laslabs/odoo,microcom/odoo,ygol/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo