Comment typo.

From-SVN: r86660

libgfortran/io/rewind.c

@@ -41,7 +41,7 @@ st_rewind (void)
       else
 	{
 	  /* If we have been writing to the file, the last written record
-	     is the last record in the file, so trincate the file now.
+	     is the last record in the file, so truncate the file now.
 	     Reset to read mode so two consecutive rewind statements
 	     don't delete the file contents.  */
           if (u->mode==WRITING)