bsdinstall: Use pkgbase.f.o for BETA/RC/RELEASE

For BETA/RC/RELEASE builds, fetch files from the appropriate repository
on pkgbase.freebsd.org, using the appropriate signing keys.  Note that
there is a separate repository for each BETA and RC; this ensures that
someone installing from e.g. a 15.0-RC1 ISO will get 15.0-RC1 bits and
not whatever happens to be the most recent build from releng/15.0.

With hat:	re
MFC after:	8 hours (needed in 15.0-RC1)

usr.sbin/bsdinstall/FreeBSD-base.conf.in

@@ -1,7 +1,7 @@
 FreeBSD-base: {
-  url: "pkg+https://pkg.FreeBSD.org/${ABI}/%%SUBURL%%",
+  url: "pkg+https://%%PKGHOST%%.FreeBSD.org/${ABI}/%%SUBURL%%",
   mirror_type: "srv",
   signature_type: "fingerprints",
-  fingerprints: "/usr/share/keys/pkg",
+  fingerprints: "/usr/share/keys/%%KEYSDIR%%",
   enabled: yes
 }

usr.sbin/bsdinstall/Makefile

@@ -21,16 +21,26 @@ _REVISION!=	${MAKE} -C ${SRCTOP}/release -V REVISION
 REVISION?=	${_REVISION}
 
 .if ${BRANCH} == CURRENT || ${BRANCH} == STABLE
+PKGHOST=	pkg
+KEYSDIR=	pkg
 SUBURL=		base_latest
-.elif ${BRANCH} == RELEASE || ${BRANCH:C/[0-9]+$//} == BETA || \
-    ${BRANCH:C/[0-9]+$//} == RC
+.elif ${BRANCH} == RELEASE
+PKGHOST=	pkgbase
+KEYSDIR=	pkgbase-${REVISION:C/\.[0-9]+//}
 SUBURL=		base_release_${REVISION:C/[0-9]+\.//}
+.elif ${BRANCH:C/[0-9]+$//} == BETA || \
+    ${BRANCH:C/[0-9]+$//} == RC
+PKGHOST=	pkgbase
+KEYSDIR=	pkgbase-${REVISION:C/\.[0-9]+//}
+SUBURL= 	base_release_${REVISION:C/[0-9]+\.//}_${BRANCH:tl}
 .else
 .warning Invalid branch "${BRANCH}"
+PKGHOST=	pkg
+KEYSDIR=	pkg
 SUBURL=		base_latest
 .endif
 
 FreeBSD-base.conf: FreeBSD-base.conf.in
-	sed "s|%%SUBURL%%|${SUBURL}|" < ${.ALLSRC} > ${.TARGET}
+	sed "s|%%PKGHOST%%|${PKGHOST}|;s|%%SUBURL%%|${SUBURL}|;s|%%KEYSDIR%%|${KEYSDIR}|" < ${.ALLSRC} > ${.TARGET}
 
 .include <bsd.prog.mk>