Build: pass down %{release} from SPEC to configure

This is required in order to bake-in precise vendor version to
version.py.

https://fedorahosted.org/freeipa/ticket/6418

Reviewed-By: Tomas Krizek <tkrizek@redhat.com>

freeipa.spec.in

@@ -687,7 +687,7 @@ This package contains tests that verify IPA functionality under Python 3.
 %build
 # UI compilation segfaulted on some arches when the stack was lower (#1040576)
 export JAVA_STACK_SIZE="8m"
-%configure
+%configure --with-vendor-suffix=-%{release}
 %make_build