Fix preload-link-to-exe case, tweaking symbol visibilities, and minor cleanups. Don't use protected visibility for global data, since it means we get two copies between exe and preload lib.
tests: simple-client passes if it builds and doesn't crash.
Undo overzealous pruning of archive targets, and erroneous deletion of fake liballocs.so linker script.
Fix egregiously wrong biggest_vaddr_in_object, so that it looks at all phdrs in one object instead of the first in each.
Better .hgignore.
Actually add simple-client test case.
.hgignore: more tweaks.
Merge build-fix / -lallocs changes.