a422d893b8
With --enable-memchecker builds, use calloc(3) for OBJ_NEW instead of malloc(3). This cuts down on a lot of valgrind/memory checker false positive output. Also make a minor change in the valgrind configure.m4; have it assign 0xf to a char. The prior assignment (of 0xff) was warning about an overflow. This didn't really matter, but we might as well make the test not have a gratuitious warning in it.