Unused options in build process

[egelmex]

From trac reported by @jadudm:
We pass configuration options down through the build process that are unrecognized in some parts of the tree. This causes warnings during the build process that confuse new developers.

[atsampson]

I think this is bitrot in occam-subdirs.m4 -- the autoconf macro it's based on now uses AC_DISABLE_OPTION_CHECKING to turn off these warnings for subdirectories, so adding that would probably fix it.

In the longer term it'd be better to get rid of the recursive autoconf/make entirely... but that's a lot more work!