[PATCH] packaging: fix "make centos{5,6,7}"

[Antonio Muci]

# HG changeset patch
# User muxator <a.mux at inwind.it>
# Date 1539277362 -7200
#      Thu Oct 11 19:02:42 2018 +0200
# Node ID 6c5ae5bfae9f44950c041980f446310ea3f96dd3
# Parent  89742f1fa6cbf176259d694377aae17a0f7cd88d
packaging: fix "make centos{5,6,7}"

Without this change, make centos{5,6,7} fails with error:
    cp: cannot stat '<basedir>/rpmbuild/RPMS/*/*': No such file or directory

This change is the exact equivalent of bc4bbc42899a (which applied to Fedora).

diff --git a/contrib/packaging/Makefile b/contrib/packaging/Makefile
--- a/contrib/packaging/Makefile
+++ b/contrib/packaging/Makefile
@@ -120,8 +120,8 @@ define centos_targets
 centos$(1):
 	mkdir -p $$(HGROOT)/packages/centos$(1)
 	./buildrpm $$(if $$(filter $(1),$$(CENTOS_WITH_PYTHON_RELEASES)),--withpython)
-	cp $$(HGROOT)/rpmbuild/RPMS/*/* $$(HGROOT)/packages/centos$(1)
-	cp $$(HGROOT)/rpmbuild/SRPMS/* $$(HGROOT)/packages/centos$(1)
+	cp $$(HGROOT)/contrib/packaging/rpmbuild/RPMS/*/* $$(HGROOT)/packages/centos$(1)
+	cp $$(HGROOT)/contrib/packaging/rpmbuild/SRPMS/* $$(HGROOT)/packages/centos$(1)
 
 .PHONY: docker-centos$(1)
 docker-centos$(1):