Thanks, that worked very well. It still has to be manually updated but at
least now it only needs to be updated in one place (and committed).
I had to change the command though to <target-os>windows and to use a full
windows path. I guess I'm using a somewhat mixed environment; I'm
building with <target-os>windows but using cygwin's gcc (which is the only
gcc I have installed). This is the final command that I used (in
Jamroot):
project
: requirements
<target-os>windows:<include>d:/cygwin/usr/include/boost-1_33_1
<target-os>linux:<library>rt
;