source-builder want to add CFLAG

[junkes]

I want to add the CFLAG "-DHAVE_MKTIME=1" to the source-builder process 
to build ntp

../source-builder/sb-set-builder --log=log_ntp_arm.txt 
--prefix=/home/h1/GSOC/RTEMS/5.0.0-m2003 \
--host=arm-rtems5 --with-rtems-bsp=xilinx_zynq_a9_qemu net/ntp

I have already tried several places (cfg-files) but without success.

Danke,
Heinz