Import NetBSD tools and build.sh

This commit finalizes support for cross compilation. The tools
directory are all links to the actual tools and are built on the
host system to build Minix. build.sh is the work horse that takes
care of all environment settings. It's slightly adjusted for Minix.
The /usr/src/Makefile has additional targets needed for cross
compilation.

tools/Makefile.gnuwrap

@@ -0,0 +1,33 @@
+#	$NetBSD: Makefile.gnuwrap,v 1.9 2003/03/14 05:22:51 thorpej Exp $
+#
+# Wrapper for GNU Makefiles.
+
+.ifndef _WRAPPER_INCLUDED
+_WRAPPER_INCLUDED=1
+
+.ifndef _NOWRAPPER
+.include "${.CURDIR}/Makefile"
+.endif
+
+# Prevent targets in source directories from being rebuilt.
+
+_srcdir:=	${srcdir}
+.MADE:		${.ALLTARGETS:M${_srcdir}/*} Makefile
+
+# Don't rebuild .gmo files, or lex/yacc (which GNU puts in the source tree).
+.po.gmo .l.c .y.c .y.h .x.1:
+	@true
+
+# Make sure this file gets re-loaded recursively.
+.ifndef _NOWRAPPER
+# Some systems have a small ARG_MAX.  On such systems, prevent Make
+# variables set on the command line from being exported in the
+# environment (they will still be set in MAKEOVERRIDES).
+BUILD_OSTYPE!=  uname -s
+.if ${BUILD_OSTYPE} == "Darwin" || ${BUILD_OSTYPE} == "FreeBSD"
+__noenvexport=  -X
+.endif
+_GNUWRAPPER:=	${.PARSEDIR}/${.PARSEFILE}
+MAKE:=		${MAKE} ${__noenvexport} -f ${_GNUWRAPPER}
+.endif
+.endif