[m-dev.] gh72 test failures at higher optimization levels

[Julien Fischer]

Hi,

The recently added tests for github issue #72, fail with rotd-2021-01-13
at higher optimization levels (e.g. -O5 --intermodule-optimization), due
to map lookup aborts.

Affected tests are:

FAILED TEST hard_coded/direct_arg_partial_inst in grade hlc.gc
FAILED TEST hard_coded/gh72a in grade hlc.gc
FAILED TEST hard_coded/gh72 in grade hlc.gc
FAILED TEST hard_coded/gh72b in grade hlc.gc
FAILED TEST invalid/gh72_errors-nodepend in grade hlc.gc
FAILED TEST valid/dupelim_mkword_hole in grade hlc.gc

(Further details can be found on testing.mercurlang.org.)

Julien.