Compile fix for Solaris.

diff --git a/windows/dialog.c b/windows/dialog.c
index 4bf74b5..fa6e8a7 100644
--- a/windows/dialog.c
+++ b/windows/dialog.c
@@ -5,7 +5,7 @@
  */
 
 #include <ctype.h>
-#include <sys/errno.h>
+#include <errno.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>