make arch-independent ports

Hi,
When I try to `make package' on a port annotated with PKG_ARCH=* like
devel/uthash for instance I run into the following error:

make: don't know how to make /usr/ports/packages/amd64/all//uthash-2.3.0.tgz (prerequisite of: _internal-package-only)

Removing the extra slash solves the issue. This not my regular
territory, does it look like a reasonable fix?

Index: infrastructure/mk/bsd.port.mk
===================================================================
RCS file: /cvs/ports/infrastructure/mk/bsd.port.mk,v
retrieving revision 1.1556
diff -u -p -r1.1556 bsd.port.mk
--- infrastructure/mk/bsd.port.mk 13 Sep 2021 15:40:02 -0000 1.1556
+++ infrastructure/mk/bsd.port.mk 24 Sep 2021 05:50:31 -0000
@@ -991,7 +991,7 @@ _CACHE_PACKAGE_COOKIES += ${_CACHE_REPO}
.for _S in ${BUILD_PACKAGES}
. if ${PKG_ARCH${_S}} == "*" && ${NO_ARCH} != ${MACHINE_ARCH}/all
_PACKAGE_LINKS += ${MACHINE_ARCH}/all/${_PKGFILE${_S}} ${NO_ARCH}/${_PKGFILE${_S}}
-_PACKAGE_COOKIES${_S} += ${_PKG_REPO}/${_PKGFILE${_S}}
+_PACKAGE_COOKIES${_S} += ${_PKG_REPO}${_PKGFILE${_S}}
. endif
_PACKAGE_COOKIES${_S} += ${_PACKAGE_COOKIE${_S}}
. if ${PERMIT_PACKAGE${_S}:L} == "yes"