Currently we just emit a generic 'not implemented' diagnostic for all
OpenACC pragmas. This patch moves the diagnostic to 'Sema' and diagnoses
for a specific clause or construct, in preperation of implementing Sema
for constructs.
'bind' takes either a string literal, or an 'identifier' representing
the device-side function that this routine is intended to 'bind' to
(that is, to call). However, it seems that the intent is to permit the
'identifier' to reference any function, thus we're implementing this as
an ID expression.
Additionally, while working on this I discovered that the 'routine' ID
expression parsing for C++ wouldn't allow non-static member functions to
be referenced since it expected us to call it, this was fixed as a part
of this patch as the 'bind' support needed it too. A test was added for
routine.
The 'routine' construct applies either to a function directly, or, when
provided a name, applies to the function named (and is visible in the
current scope). This patch implements the parsing for this. The
identifier provided (or Id Expression) is required to be a valid,
declared identifier, though the semantic analysis portion of the Routine
directive will need to enforce it being a function/overload set.
