api.static_maps_mixup_novars is flaky

static_maps_mixup_novars and static_maps_mixup_yesvars are tests which verify that setting linker vars for static+linux binaries has the expected effects from an end-to-end perspective (including the linker correctly passing along expected values). Both tests run the same code to mix up their /proc/self/maps and then run a static attach+detach, with the only difference being that the 'yesvars' version supplies the linker variables and is expected to pass whereas the 'novars' version is expected to fail for one reason or another due to the mixed up maps file.

On some platforms (e.g. [CDash](http://dynamorio.org/CDash/testSummary.php?project=1&name=code_api|api.static_maps_mixup_novars&date=2019-04-12)) it appears that the 'novars' can pass in some cases anyway. Perhaps I can try harder in mixing up the maps files.