R600: Add option to disable promote alloca

This can make writing some tests harder, so add a flag
to disable it.
R600: Run private-memory test with and without alloca promote

The unpromoted path still needs to be tested since we can't
always promote to using LDS.
R600: Run more tests with promote alloca disabled.

Re-run tests changed in r211110 to test both paths.
Also fix broken check line.