Fix building on slightly older -current and stable systems after

the switch to bmake. The rescue bits are built via crunchgen,
which didn't respect the MAKE environment variable until r237574
(i.e. ~11 months ago). This resulted in a failure due to bmake's
internal -J flag being passed around and not being understood by
the standard (i.e. host's) make.
Note that the failure is conditional upon having the jobServer
feature enabled within bmake.

Makefile.inc1

@@ -1215,6 +1215,10 @@ _yacc=		lib/liby \
 		usr.bin/yacc
 .endif
 
+.if ${BOOTSTRAPPING} < 1000014
+_crunch=	usr.sbin/crunch
+.endif
+
 .if ${BOOTSTRAPPING} < 1000026
 _nmtree=	lib/libnetbsd \
 		usr.sbin/nmtree
@@ -1293,6 +1297,7 @@ bootstrap-tools:
     usr.bin/xinstall \
     ${_gensnmptree} \
     usr.sbin/config \
+    ${_crunch} \
     ${_nmtree}
 	${_+_}@${ECHODIR} "===> ${_tool} (obj,depend,all,install)"; \
 		cd ${.CURDIR}/${_tool}; \