allow converting static vars to openArray (#19049)

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 490c4226a5)

compiler/ccgcalls.nim

@@ -189,7 +189,7 @@ proc openArrayLoc(p: BProc, formalType: PType, n: PNode): Rope =
       internalError(p.config, "openArrayLoc: " & typeToString(a.t))
   else:
     initLocExpr(p, n, a)
-    case skipTypes(a.t, abstractVar).kind
+    case skipTypes(a.t, abstractVar+{tyStatic}).kind
     of tyOpenArray, tyVarargs:
       result = "$1, $1Len_0" % [rdLoc(a)]
     of tyString, tySequence: