use libc.h from ../lib9
turn on warnings and -T

Reference: /n/atom/patch/applied2013/drawbsd
Date: Mon Jun  3 17:48:35 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/ape/lib/draw/mkfile	Mon Jun  3 17:48:35 2013
+++ /sys/src/ape/lib/draw/mkfile	Mon Jun  3 17:48:35 2013
@@ -69,7 +69,7 @@
 
 </sys/src/cmd/mksyslib
 
-CFLAGS=-Vwc $CFLAGS -D_POSIX_SOURCE -D_PLAN9_SOURCE -I.
+CFLAGS=-TVwc $CFLAGS -D_POSIX_SOURCE -D_PLAN9_SOURCE -I. -I../9
 
 %.$O: /sys/src/libdraw/%.c
 	$CC $CFLAGS /sys/src/libdraw/$stem.c