Polymorphic temporary are currently propagated as
fir.ref<fir.class<fir.heap<>>> because their allocation may be delayed
to the hlfir.assign copy (using realloc).
This patch moves away from this and directly allocate the temp and
propagate it as a fir.class.
The polymorphic temporaries creating is also simplified by avoiding the
need to call the runtime to setup the descriptor altogether (the runtime
is still call for the allocation currently because alloca/allocmem do
not support polymorphism).
Extends support for locality specifiers in `do concurrent` by supporting
data types that need `init` regions.
This further unifies the paths taken by the compiler for OpenMP
privatization clauses and `do concurrent` locality specifiers.
This PR extends `genSymbolType` so that the type of an associating
symbol carries the shape of the selector expression, if any. This is a
fix for a bug that triggered when an associating symbol is used in a
locality specifier. For example, given the following input:
```fortran
associate(a => aa(4:))
do concurrent (i = 4:11) local(a)
a(i) = 0
end do
end associate
```
before the changes in the PR, flang would assert that we are casting
between incompatible types. The issue happened since for the associating
symbol (`a`), flang generated its type as `f32` rather than
`!fir.array<8xf32>` as it should be in this case.
