How CPPFLAGS.file.c=xxx should work?

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Hi

Considering the following Makefile:

NETBSDSRCDIR=   /netbsd-src
DISTRIBDIR=     ${NETBSDSRCDIR}/distrib
.include                <bsd.own.mk>
HACKSRC=        ${DISTRIBDIR}/utils/libhack
.include                "${HACKSRC}/Makefile.inc"  
all:            libhack.o

I use it:
/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/nbmake-i386
/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c /netbsd-src/distrib/utils/libhack/getnetgr.c/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c
/netbsd-src/distrib/utils/libhack/getpwent.c
/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c /netbsd-src/distrib/utils/libhack/localeconv.c/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c
/netbsd-src/distrib/utils/libhack/multibyte.c/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c /netbsd-src/distrib/utils/libhack/perror.c
/netbsd-obj/tooldir.NetBSD-6.1.2-i386/bin/i486--netbsdelf-gcc -O2  --sysroot=/netbsd-obj/destdir.i386 -DSMALL -c /netbsd-src/distrib/utils/libhack/../../../lib/libc/locale/runetable.c
/netbsd-src/distrib/utils/libhack/../../../lib/libc/locale/runetable.c:50:27: fatal error: citrus_module.h: No such file or directory
 #include "citrus_module.h"

citrus_module.h is in /netbsd-src/lib/libc/citrus for whitch there is no -I flag. 
Looking in /netbsd-src/distrib/utils/libhack/Makefile.inc  I find:

CPPFLAGS.runetable.c+= -I${HACKSRC}/../../../lib/libc/citrus \
                        -DALL_80_TO_FF_SW1

So this CPPFLAGS.file.c is not honoured. Why? What did I failed to do?

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost