Move some LIBCOMPAT tmpdir logic setup to its own build target.

Its own build target was already handling mtree extractions
just as _worldtmp did, so the other cleaning of the
tmpdir makes sense here as well.

Sponsored by:	Dell EMC Isilon

Makefile.inc1

@@ -817,19 +817,11 @@ _worldtmp: .PHONY
 	@echo "--------------------------------------------------------------"
 .if !defined(NO_CLEAN)
 	rm -rf ${WORLDTMP}
-.if defined(LIBCOMPAT)
-	rm -rf ${LIBCOMPATTMP}
-.endif
 .else
 .if exists(${WORLDTMP})
 	@echo ">>> Deleting stale files in build tree..."
 	${_+_}cd ${.CURDIR}; ${WMAKE} -DBATCH_DELETE_OLD_FILES \
 	    delete-old delete-old-libs >/dev/null
-.endif
-.if defined(LIBCOMPAT) && exists(${LIBCOMPATTMP})
-	${_+_}cd ${.CURDIR}; ${WMAKE} -DBATCH_DELETE_OLD_FILES \
-	    DESTDIR=${LIBCOMPATTMP} \
-	    delete-old delete-old-libs >/dev/null
 .endif
 	rm -rf ${WORLDTMP}/legacy/usr/include
 .if ${USING_SYSTEM_COMPILER} == "yes"

Makefile.libcompat

@@ -148,6 +148,16 @@ build${libcompat}: .PHONY
 	@echo "--------------------------------------------------------------"
 	@echo ">>> stage 5.1: building lib${libcompat} shim libraries"
 	@echo "--------------------------------------------------------------"
+.if !defined(NO_CLEAN)
+	rm -rf ${LIBCOMPATTMP}
+.else
+.if exists(${LIBCOMPATTMP})
+	${_+_}cd ${.CURDIR}; ${WMAKE} -DBATCH_DELETE_OLD_FILES \
+	    DESTDIR=${LIBCOMPATTMP} \
+	    delete-old delete-old-libs >/dev/null
+.endif
+.endif	# !defined(NO_CLEAN)
+
 	mkdir -p ${LIBCOMPATTMP}/usr/include
 	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.usr.dist \
 	    -p ${LIBCOMPATTMP}/usr >/dev/null