opencryptoki fails to cross build from source for two reasons. The
immediate failure is a bit crazy as it results from $(CC_FOR_BUILD)
ending up being empty. This is due to running autoreconf without
installing autoconf-archive and therefore AX_CC_FOR_BUILD not being
substituted. Once substituted the build proceeds much further until a
build-time tools fails to be built due to missing a macro. This macro is
set for the host's CFLAGS and also needs to be set in CFLAGS_FOR_BUILD.
I'm attaching a patch addressing both problems for your convenience.
Please consider applying it and forwarding the upstream parts upstream.

Helmut