* Process a standard command-line parameter. `p' is the parameter
* in question; `value' is the subsequent element of argv, which
* may or may not be required as an operand to the parameter.
+ * If `need_save' is 1, arguments which need to be saved as
+ * described at this top of this file are, for later execution;
+ * if 0, they are processed normally. (-1 is a special value used
+ * by pterm to count arguments for a preliminary pass through the
+ * argument list; it causes immediate return with an appropriate
+ * value with no action taken.)
* Return value is 2 if both arguments were used; 1 if only p was
* used; 0 if the parameter wasn't one we recognised; -2 if it
* should have been 2 but value was NULL.