bsd.port.mk: make update-patches depend on patch

Logically obvious to me; any reasons not to do it?

Basically, I expected this dependency when updating a port but was
mistaken:

$ make extract
[...]
$ make update-patches
WRKDIST=/usr/ports/pobj/git-2.22.0/git-2.22.0 does not exist
*** Error 1 in /usr/ports/devel/git (/usr/ports/infrastructure/mk/bsd.port.mk:2467 'update-patches': @toedit=`WRKDIST=/usr/ports/pobj/git-2....)

Feedback? OK?

Index: bsd.port.mk
===================================================================
RCS file: /cvs/ports/infrastructure/mk/bsd.port.mk,v
retrieving revision 1.1471
diff -u -p -r1.1471 bsd.port.mk
--- bsd.port.mk 16 Jun 2019 14:27:42 -0000 1.1471
+++ bsd.port.mk 24 Jun 2019 21:51:25 -0000
@@ -2457,7 +2457,7 @@ _internal-plist _internal-update-plist:
@${_MAKE} _internal-generate-readmes
@${_update_plist}

-update-patches:
+update-patches: ${_PATCH_COOKIE}
@toedit=`WRKDIST=${WRKDIST} PATCHDIR=${PATCHDIR} \
PATCH_LIST='${PATCH_LIST}' DIFF_ARGS='${DIFF_ARGS}' \
DISTORIG=${DISTORIG} PATCHORIG=${PATCHORIG} \