[flang] Add entry points for internal scalar list-directed I/O

[klausler]

Summary

BeginInternalListInput and BeginInternalListOutput were missing
from the I/O API implementation; add them.

[PeteSteinfeld]

The changes build and test OK, except that the test Semantics/omp-clause-validity01.f90 fails, which I'm sure is unrelated.

The changes look OK to me, but I don't really understand them. Someone more familiar with the code might want to weigh in.

flang/runtime/io-api.cpp

 Cookie IONAME(BeginInternalArrayFormattedInput)(const Descriptor &descriptor,
     const char *format, std::size_t formatLength, void **scratchArea,
     std::size_t scratchBytes, const char *sourceFile, int sourceLine) {
   return BeginInternalArrayFormattedIO<Direction::Input>(descriptor, format,
       formatLength, scratchArea, scratchBytes, sourceFile, sourceLine);
 }
 
 template <Direction DIR>
+Cookie BeginInternalListIO(
+    std::conditional_t<DIR == Direction::Input, const char, char> *internal,
+    std::size_t internalLength, void ** /*scratchArea*/,
+    std::size_t /*scratchBytes*/, const char *sourceFile, int sourceLine) {
+  Terminator oom{sourceFile, sourceLine};
+  return &New<InternalListIoStatementState<DIR>>{oom}(
+      internal, internalLength, sourceFile, sourceLine)
+              .release()
+              ->ioStatementState();
+}
+
+Cookie IONAME(BeginInternalListOutput)(char *internal,
+    std::size_t internalLength, void **scratchArea, std::size_t scratchBytes,
+    const char *sourceFile, int sourceLine) {
+  return BeginInternalListIO<Direction::Output>(internal, internalLength,
+      scratchArea, scratchBytes, sourceFile, sourceLine);
+}
+
+Cookie IONAME(BeginInternalListInput)(const char *internal,
+    std::size_t internalLength, void **scratchArea, std::size_t scratchBytes,
+    const char *sourceFile, int sourceLine) {
+  return BeginInternalListIO<Direction::Input>(internal, internalLength,
+      scratchArea, scratchBytes, sourceFile, sourceLine);
+}
+
+template <Direction DIR>
 Cookie BeginInternalFormattedIO(
     std::conditional_t<DIR == Direction::Input, const char, char> *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     void ** /*scratchArea*/, std::size_t /*scratchBytes*/,
     const char *sourceFile, int sourceLine) {
   Terminator oom{sourceFile, sourceLine};
   return &New<InternalFormattedIoStatementState<DIR>>{oom}(
       internal, internalLength, format, formatLength, sourceFile, sourceLine)
               .release()
               ->ioStatementState();
 }
 
 Cookie IONAME(BeginInternalFormattedOutput)(char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     void **scratchArea, std::size_t scratchBytes, const char *sourceFile,
     int sourceLine) {
-  Terminator oom{sourceFile, sourceLine};
   return BeginInternalFormattedIO<Direction::Output>(internal, internalLength,
       format, formatLength, scratchArea, scratchBytes, sourceFile, sourceLine);
 }
 
 Cookie IONAME(BeginInternalFormattedInput)(const char *internal,
     std::size_t internalLength, const char *format, std::size_t formatLength,
     void **scratchArea, std::size_t scratchBytes, const char *sourceFile,
     int sourceLine) {
-  Terminator oom{sourceFile, sourceLine};
   return BeginInternalFormattedIO<Direction::Input>(internal, internalLength,
       format, formatLength, scratchArea, scratchBytes, sourceFile, sourceLine);
 }
 
 template <Direction DIR>
 Cookie BeginExternalListIO(
     ExternalUnit unitNumber, const char *sourceFile, int sourceLine) {
   Terminator terminator{sourceFile, sourceLine};