. if the layout of virtual address regions as returned
by mmap() without a location hint changes, ld.so could
trip itself up (under minix). this change allocates
the full size it needs for every object that's loaded
so that if that succeeds, it's sure there's virtual address
space for the whole thing no matter what other bits happen
to be there already.
. this fix exposed a bug in the test; at atexit() execution
time the loaded object is unmapped, so that part of the
test is removed.
. so that functionality is tested
. add test63 that actually tests dlopen(), dlsym(),
etc. functionality; only built if clang supports it
. also test10 test to copy more of the executable
