Simplify the hierarchy target's logic. [0]

Run hierarchy with WORLDTMP in the path so it works when it is invoked
directly.  Such use is nearly alwasy wrong but appears to be common.[1]

PR:		conf/178209 [0], conf/178547 [1]
Submitted by:	Garrett Cooper <yaneurabeya@gmail.com> [0]
MFC after:	5 days

Makefile.inc1

@@ -263,6 +263,13 @@ WMAKEENV=	${CROSSENV} \
 		VERSION="${VERSION}" \
 		INSTALL="sh ${.CURDIR}/tools/install.sh" \
 		PATH=${TMPPATH}
+
+# make hierarchy
+HMAKE=		PATH=${TMPPATH} ${MAKE} LOCAL_MTREE=${LOCAL_MTREE}
+.if defined(NO_ROOT)
+HMAKE+=		PATH=${TMPPATH} METALOG=${METALOG} -DNO_ROOT
+.endif
+
 .if ${MK_CDDL} == "no"
 WMAKEENV+=	NO_CTF=1
 .endif
@@ -1367,12 +1374,7 @@ cross-tools:
 # hierarchy - ensure that all the needed directories are present
 #
 hierarchy hier:
-.if defined(NO_ROOT)
-	cd ${.CURDIR}/etc; ${MAKE} LOCAL_MTREE=${LOCAL_MTREE} \
-	    -DNO_ROOT METALOG=${METALOG} distrib-dirs
-.else
-	cd ${.CURDIR}/etc; ${MAKE} LOCAL_MTREE=${LOCAL_MTREE} distrib-dirs
-.endif
+	cd ${.CURDIR}/etc && ${HMAKE} distrib-dirs
 
 #
 # libraries - build all libraries, and install them under ${DESTDIR}.