Slightly loosen a test that has failed on 32-bit build lately.
Since 16d9c3a, this test was failing on all builds. The present change in not 32-bit specific; it's expected to fix this particular test, on all builds.
Note there are further 32-bit issues remaining, even after this fix.
Test is: array-collections/c-dependent
Loosening is: Adjust test's scope to avoid exercising "truly incorrect" C code; which may receive compile-time array-bound warnings on sufficiently advanced C compilers. In test code and .expect, switch from passing incorrect bounds to passing correct bounds; the point of the test (newly clarified, always foremost) is that CFA handles C's dependently sized VLA parameter.
