packages: Allow actually building individual world packages in parallel.

MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon

Makefile.inc1

@@ -1572,22 +1572,32 @@ create-world-packages:	_pkgbootstrap .PHONY
 	@for plist in ${WSTAGEDIR}/*.plist; do \
 	  plist=$${plist##*/} ; \
 	  pkgname=$${plist%.plist} ; \
-		sh ${SRCDIR}/release/packages/generate-ucl.sh -o $${pkgname} \
-			-s ${SRCDIR} -u ${WSTAGEDIR}/$${pkgname}.ucl ; \
-	done
-	@for plist in ${WSTAGEDIR}/*.plist; do \
-		plist=$${plist##*/} ; \
-		pkgname=$${plist%.plist} ; \
-		awk -F\" ' \
+	  echo "_PKGS+= $${pkgname}" ; \
+	done > ${WSTAGEDIR}/packages.mk
+	${_+_}@cd ${.CURDIR}; \
+		${MAKE} -f Makefile.inc1 create-world-packages-jobs \
+		.MAKE.JOB.PREFIX=
+
+.if make(create-world-packages-jobs)
+.include "${WSTAGEDIR}/packages.mk"
+.endif
+
+create-world-packages-jobs: .PHONY
+.for pkgname in ${_PKGS}
+create-world-packages-jobs: create-world-package-${pkgname}
+create-world-package-${pkgname}: .PHONY
+	@sh ${SRCDIR}/release/packages/generate-ucl.sh -o ${pkgname} \
+		-s ${SRCDIR} -u ${WSTAGEDIR}/${pkgname}.ucl
+	@awk -F\" ' \
 		/^name/ { printf("===> Creating %s-", $$2); next } \
 		/^version/ { print $$2; next } \
-			' ${WSTAGEDIR}/$${pkgname}.ucl ; \
+		' ${WSTAGEDIR}/${pkgname}.ucl ; \
 	${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/bin/sh -o ALLOW_BASE_SHLIBS=yes \
-			create -M ${WSTAGEDIR}/$${pkgname}.ucl \
-			-p ${WSTAGEDIR}/$${pkgname}.plist \
+		create -M ${WSTAGEDIR}/${pkgname}.ucl \
+		-p ${WSTAGEDIR}/${pkgname}.plist \
 		-r ${WSTAGEDIR} \
-			-o ${REPODIR}/$$(${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/bin/sh config ABI)/${PKG_VERSION} ; \
-	done
+		-o ${REPODIR}/$$(${PKG_CMD} -o ABI_FILE=${WSTAGEDIR}/bin/sh config ABI)/${PKG_VERSION}
+.endfor
 
 create-kernel-packages:	_pkgbootstrap .PHONY
 .if exists(${KSTAGEDIR}/kernel.meta)