allow converting static vars to openArray (#19048)

When assigning constant output to a seq, and then passing that static
seq to other functions that take `openArray`, the compiler may end up
producing errors, as it does not know how to convert `static[seq[T]]`
to `openArray[T]`. By ignoring the `static` wrapper on the type for
the purpose of determining data memory location and length, this gets
resolved cleanly. Unfortunately, it is relatively tricky to come up
with a minimal example, as there are followup problems from the failing
conversion, e.g., this may lead to `internal error: inconsistent
environment type`, instead of the relevant `openArrayLoc` error message.

(cherry picked from commit 490c422)

compiler/ccgcalls.nim

@@ -214,7 +214,7 @@ proc openArrayLoc(p: BProc, formalType: PType, n: PNode): Rope =
   else:
     var a: TLoc
     initLocExpr(p, if n.kind == nkHiddenStdConv: n[1] else: n, a)
-    case skipTypes(a.t, abstractVar).kind
+    case skipTypes(a.t, abstractVar+{tyStatic}).kind
     of tyOpenArray, tyVarargs:
       if reifiedOpenArray(n):
         if a.t.kind in {tyVar, tyLent}: