[Fortran][gfortran] Clean up pointer_check_<N>.f90 test annotations (#487)

Follow up to #483.

Flang does not implement -fcheck=pointer, and many of the tests
include UB that's supposed to be caught by that feature.

1,2,3 and 4 "fail" by crashing, which could change in future
to anything, so disable them, pointer_check_10 requires a standard
we don't support.

A lof of them are "xfailed" in test.cmake, because update-test-config.py
knows that Flang doesn't support the flag.

So we will have a disable in DisabledFiles.cmake, and an xfail in
tests.cmake. Which is odd but I think that's the way it's supposed
to work. The disable will always win.