[flang][runtime] Fix list-directed/NAMELIST complex input with "r*" repetition count

[klausler]

Summary

The little state machine in GetNextDataEdit() wasn't transitioning
properly from reading the imaginary part of the number back to the
real part for the next iteration of a repeated value.

flang/runtime/io-stmt.cpp

if (!imaginaryPart_) {
         // "r*" repeated null
         edit.descriptor = DataEdit::ListDirectedNullValue;
       }
     }
     remaining_ -= edit.repeat;
     if (remaining_ > 0) {
       repeatPosition_.emplace(io);
     }
+    if (!imaginaryPart_) {
       return edit;
     }
+  }
   // Skip separators, handle a "r*c" repeat count; see 13.10.2 in Fortran 2018
   if (imaginaryPart_) {
     imaginaryPart_ = false;
   } else if (realPart_) {
     realPart_ = false;
     imaginaryPart_ = true;
     edit.descriptor = DataEdit::ListDirectedImaginaryPart;
   }