[flang] Don't duplicate impure function call for UBOUND() (#153648)
Because the per-dimension information in a descriptor holds an extent
and a lower bound, but not an upper bound, the calculation of the upper
bound sometimes requires that the extent and lower bound be extracted
from a descriptor and added together, minus 1. This shouldn't be
attempted when the NamedEntity of the descriptor is something that
shouldn't be duplicated and used twice; specifically, it shouldn't apply
to NamedEntities containing references to impure functions as parts of
subscript expressions.
Fixes https://github.com/llvm/llvm-project/issues/153031.
llvm-project
2cf982c0 - [flang] Don't duplicate impure function call for UBOUND() (#153648)
