bc and libmath.h question

[jmc <jmc_(_at_)_prioris_(_dot_)_mini_(_dot_)_pw_(_dot_)_edu_(_dot_)_pl>]

Hi.

bc refuses to compile on current, because:

make: don't know how to build libmath.h

libmath.h and dc.info are wiped out when I run make cleandir from
/usr/src. In the makefile:

CLEANFILES+=	bc/libmath.h doc/dc.info

I worked around it by moving the files back to /usr/src/gnu/usr.bin/bc
after starting my make build, and it builds fine.

Is anybody else seeing this, or can someone tell me what I've done
wrong?

Thanks,
jmc.