Do not remove check.info during 'clean' target
Do not remove check.info during 'clean' target

It was observed that if one does not have texinfo installed
and invoked "make clean" then a subsequent build will fail
because the docs cannot be built. The issue is that
"make clean" will remove check.info and require it be rebuilt.

tarruda/check,tarruda/check,tarruda/check,tarruda/check,tarruda/check