[flang][runtime] Respect PAD='NO' on READ/WRITE

[klausler]

Summary

The check for the PAD= setting should examine the mutable modes
of the current I/O statement, not the persistent modes of the
I/O unit.

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) {
+        const auto &modes{mutableModes()};
+        if (modes.nonAdvancing) {
           if (connection.access == Access::Stream &&
               connection.unterminatedRecord) {
             // Reading final unterminated record left by a
             // non-advancing WRITE on a stream file prior to
             // positioning or ENDFILE.
             handler.SignalEnd();
           } else {
             handler.SignalEor();
           }
-        } else if (!connection.modes.pad) {
+        } else if (!modes.pad) {
           handler.SignalError(IostatRecordReadOverrun);
         }
-        return connection.modes.pad; // PAD='YES'
+        return modes.pad; // PAD='YES'
       }
     }
   }
   return false;
 }
 
 bool IoStatementState::Inquire(
     InquiryKeywordHash inquiry, char *out, std::size_t chars) {