[CodeGen] Workaround for compiler crash
This patch implements a workaround for a "Getting frame offset for a dead
object?" assertion triggered when compiling the target-generic-loops.f90
offloading test. A more concise reproducer for this issue:
```f90
! flang -O0 -fopenmp -fopenmp-version=52 --offload-arch=gfx1100 test.f90
program main
integer :: i, counter
!$omp target teams distribute
do i=1, 10
end do
counter = 0
!$omp target map(tofrom: counter)
!$omp parallel do reduction(+:counter)
do i=1, 10
counter = counter + 1
end do
!$omp end target
end program
```
This is an AI-generated fix and needs a proper review by an expert in this area
of the compiler, as I am not familiar enough to evaluate whether it is a valid
approach or if there is a problem with the LLVM IR produced by Flang itself.
However, it does address the problem and causes these tests to be successfully
compiled and run as expected.
