[flang][runtime] Signal record read overrun when PAD='NO'

[klausler]

Summary

When PAD='NO' and ADVANCE='YES', we currently signal an input
error when a formatted read tries to go past the end of a record
only when a fixed RECL= is in effect. Other compilers will signal
an error without RECL= too, and that seems like a precedent we
should follow.

flang/runtime/io-stmt.cpp

 bool IoStatementState::CheckForEndOfRecord() {
   const ConnectionState &connection{GetConnectionState()};
   if (!connection.IsAtEOF()) {
     if (auto length{connection.EffectiveRecordLength()}) {
       if (connection.positionInRecord >= *length) {
         IoErrorHandler &handler{GetIoErrorHandler()};
         if (mutableModes().nonAdvancing) {
           handler.SignalEor();
-        } else if (connection.openRecl && !connection.modes.pad) {
+        } else if (!connection.modes.pad) {
           handler.SignalError(IostatRecordReadOverrun);
         }
         return connection.modes.pad; // PAD='YES'
       }
     }
   }
   return false;
 }