[Flang][OpenMP] Skip threadprivate HostAssoc symbols for default privatization (#127754)
Issue: Compilation abnormally terminates in parallel default(private)
Documentation reference:
A threadprivate variable must not appear as the base variable of a list
item in any clause except for the copyin and copyprivate clauses
Explanation:
From the reference, the threadprivate symbols cannot be used in the DSA
clauses, which in turn means, the symbol can be skipped for default
privatization
Fixes #123535