check for interrupt from fgets on Windows

[lanza]

Summary

Windows does not have the error EINTR when a blocking syscall is
interrupted by a signal. The ReadFile API that fgets is implemented
with instead use ERROR_OPERATION_ABORTED. Check for that after fgets.

[aleksandr.urakov]

LGTM!

[lanza]

This actually doesn't seem to be working due to a bug in Windows' ReadFile. https://github.com/microsoft/terminal/issues/334 @stella.stamenova any idea about this?

[lanza]

rebase

source/Core/IOHandler.cpp

if (in) {
         }
       }
       char buffer[256];
       bool done = false;
       bool got_line = false;
       m_editing = true;
       while (!done) {
         if (fgets(buffer, sizeof(buffer), in) == nullptr) {
+#ifdef _WIN32
+          // this is the equivalent of EINTR for Windows
+          if (GetLastError() == ERROR_OPERATION_ABORTED)
+            continue;
+#endif
           const int saved_errno = errno;
           if (feof(in))
             done = true;
           else if (ferror(in)) {
             if (saved_errno != EINTR)
               done = true;
           }
         } else {