Fix io_file_is_empty() behaviour when file starts with a newline.

Read second byte if the first byte is a newline character to ensure the
file doesn't contain any further data.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/io.c

@@ -3051,7 +3051,7 @@ io_file_is_empty (char *file)
 
   if (file && (fp = fopen (file, "r")))
     {
-      if (fgetc (fp) == '\n' || feof (fp))
+      if ((fgetc (fp) == '\n' && fgetc (fp) == EOF) || feof (fp))
         {
           fclose (fp);
           return 1;