[flang][OpenMP] Add optional argument to requirement clauses (#163557)

OpenMP 6.0 added an optional logical parameter to the requirement
clauses (except ATOMIC_DEFAULT_MEM_ORDER) to indicate whether the clause
should take effect or not. The parameter defaults to true if not
specified.

The parameter value is a compile-time constant expression, but it may
require folding to get the final value. Since name resolution happens
before folding, the argument expression needs to be analyzed by hand.
The determination of the value needs to happen during name resolution
because the requirement directives need to be available through module
files (and the module reader doesn't to semantic checks beyond name
resolution).

0 files changed, 0 insertions, 0 deletions