[flang] Runtime validation of SPREAD(DIM=dim) argument

[klausler]

Summary

Crash when DIM= is not a valid dimension in the result.

[PeteSteinfeld]

All builds and tests correctly and looks good.

flang/runtime/transformational.cpp

 }
 
 // SPREAD
 void RTNAME(Spread)(Descriptor &result, const Descriptor &source, int dim,
     std::int64_t ncopies, const char *sourceFile, int line) {
   Terminator terminator{sourceFile, line};
   int rank{source.rank() + 1};
   RUNTIME_CHECK(terminator, rank <= maxRank);
+  if (dim < 1 || dim > rank) {
+    terminator.Crash("SPREAD: DIM=%d argument for rank-%d source array "
+                     "must be greater than 1 and less than or equal to %d",
+        dim, rank - 1, rank);
+  }
   ncopies = std::max<std::int64_t>(ncopies, 0);
   SubscriptValue extent[maxRank];
   int k{0};
   for (int j{0}; j < rank; ++j) {
     extent[j] = j == dim - 1 ? ncopies : source.GetDimension(k++).Extent();
   }
   AllocateResult(result, source, rank, extent, terminator, "SPREAD");
   SubscriptValue resultAt[maxRank];