make -> mk.

add Bfdopen.

src/libbio/mkfile

@@ -0,0 +1,31 @@
+PLAN9=../..
+<$PLAN9/src/mkhdr
+
+LIB=libbio.a
+
+OFILES=\
+	bbuffered.$O\
+	bfildes.$O\
+	bflush.$O\
+	bgetc.$O\
+	bgetd.$O\
+	binit.$O\
+	boffset.$O\
+	bprint.$O\
+	bputc.$O\
+	brdline.$O\
+	brdstr.$O\
+	bread.$O\
+	bseek.$O\
+	bwrite.$O\
+	bgetrune.$O\
+	bputrune.$O\
+
+HFILES=\
+	$PLAN9/include/bio.h\
+
+<$PLAN9/src/mksyslib
+
+bcat: bcat.$O $LIB
+	$CC -o bcat bcat.$O -L$PLAN9/lib -lbio -lfmt -lutf
+