pkgbase: rename PKGSIGNKEY to PKG_REPO_SIGNING_KEY

this way, it'll be automatically picked up by poudriere
That's quite handy when building pkgbase!

Submitted by:	Mina Galić <me@igalic.co>
Reviewed By: bapt, bcr (manpages)
Differential Revision: https://reviews.freebsd.org/D27690

Makefile.inc1

@@ -1851,7 +1851,7 @@ WSTAGEDIR?=	${OBJTOP}/worldstage
 KSTAGEDIR?=	${OBJTOP}/kernelstage
 REPODIR?=	${OBJROOT}repo
 PKG_FORMAT?=	txz
-PKGSIGNKEY?=	# empty
+PKG_REPO_SIGNING_KEY?=	# empty
 PKG_OUTPUT_DIR?=	${PKG_VERSION}
 
 .ORDER:		stage-packages create-packages
@@ -2064,7 +2064,7 @@ sign-packages:	_pkgbootstrap .PHONY
 		-m ${WSTAGEDIR}/meta \
 		-o ${REPODIR}/$$(${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/usr/bin/uname config ABI)/${PKG_VERSION} \
 		${REPODIR}/$$(${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/usr/bin/uname config ABI)/${PKG_VERSION} \
-		${PKGSIGNKEY} ; \
+		${PKG_REPO_SIGNING_KEY} ; \
 	cd ${REPODIR}/$$(${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/usr/bin/uname config ABI); \
 	ln -s ${PKG_OUTPUT_DIR} latest
 

share/man/man5/make.conf.5

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 27, 2018
+.Dd December 20, 2020
 .Dt MAKE.CONF 5
 .Os
 .Sh NAME
@@ -444,6 +444,16 @@ statically linked, this can be bad.
 If set, every utility that uses
 .Pa bsd.prog.mk
 will be linked statically.
+.It Va PKG_REPO_SIGNING_KEY
+.Pq Vt str
+Path to rsa private key passed to
+.Xr pkg-repo 8
+to sign packages created when building the
+.Ar packages
+target, i.e.: pkgbase.
+The variable is named the same in
+.Xr poudriere 8
+so it will automatically be picked up when building pkgbase with poudriere.
 .It Va PPP_NO_NAT
 .Pq Vt bool
 Build