Allow extra directories to be added to the build-tools target.

Things such as "sh" require local tools to be built before
cross-compiling. This allows for extra software (that's
built via LOCAL_DIRS) to also have a build-tools target where
required.

Makefile.inc1

@@ -15,6 +15,8 @@
 #	-DNO_WWWUPDATE do not update www in ${MAKE} update
 #	-DNO_CTF do not run the DTrace CTF conversion tools on built objects
 #	LOCAL_DIRS="list of dirs" to add additional dirs to the SUBDIR list
+#	LOCAL_TOOL_DIRS="list of dirs" to add additional dirs to the build-tools
+#	    list
 #	TARGET="machine" to crossbuild world for a different machine type
 #	TARGET_ARCH= may be required when a TARGET supports multiple endians
 
@@ -104,6 +106,8 @@ CLEANDIR=	clean cleandepend
 CLEANDIR=	cleandir
 .endif
 
+LOCAL_TOOL_DIRS?=	''
+
 CVS?=		cvs
 CVSFLAGS?=	-A -P -d -I!
 SVN?=		svn
@@ -1101,6 +1105,7 @@ build-tools:
     bin/csh \
     bin/sh \
     ${_rescue} \
+    ${LOCAL_TOOL_DIRS} \
     lib/ncurses/ncurses \
     lib/ncurses/ncursesw \
     ${_share} \