Feature/popc quiet flag, closing #126

[sfkleach]

This adds a new flag '-quiet' to the popc compiler that suppresses the garbage collection message and also the printing of file names to stderr.

[sfkleach]

Waldek made comments as follows:

I must admit that I have doubts about this patch. Namely, there
is already a flag, namely 'l_flag' that controls printing of
files. Extra machinery, that is 'cucharverbose' to control
the same thing looks undesirable (unnecessary complexity).
I think it would be better to to set 'l_flag' to false to
get the effect.

Of course, there is a difficulty: option processing may set
'l_flag' to true after '-quiet' set it to false. One solution,
which is simple is to set 'l_flag' only due to explicit request
(that is '-l' option). Another is to change '-quiet' handling to

                elseif c == "quiet" then
                    false -> popgctrace;
                    "quiet" -> l_flag;

and assign 'l_flag or true' to 'l_flag' during option processing.

And at end add

   if l_flag == "quiet" then false -> l_flag endif;

Or, set extra variable during processing of 'quiet' and if that
variable is set assign 'false' to 'l_flag'.

Concerning build: I agree that by default it should less chatty,
but IMO this should be controlled by variable, so that one
can turn on verbosity from command line.

BTW: For build I usually use commands like

make > mlogg 2>&1

If everything goes OK I can discard 'mlogg' later. In case
of troubles verbosity may help...

[sfkleach]

I agree that using the preexisting l_flag is a less intrusive change and I have adopted Waldek's suggestion almost in its entirety. The suggestion that the verbosity should be controlled by a variable I have not followed through for these reasons.

• It is unclear whether the intention is an environment variable or a pop11 variable (e.g. some variant on pop_debugging) .
• If there is a -l flag to generate a listing then it makes sense for there to be a -q flag to inhibit the listing. To my way of thinking it is a pretty clear omission in the design of the option flags.
• It should be easy enough to incorporate this suggestion when it is clarified.

[hebisch]

First to clarify, I wrote:

: Concerning build: I agree that by default it should less chatty,
: but IMO this should be controlled by variable, so that one
: can turn on verbosity from command line.

This is not about popc. Rather I mean Makefiles for Poplog build.
And by variable I mean make variable.

Concerning patches, I have two remarks:

• As is last of -q and -l wins. I am not sure if this is useful. Code would be
  simpler if -q always wins. This is minor issue, I mention this to make sure
  that you really want this.
• In my code I am trying to keep line length below 80 characters. Your
  comments creates longer lines.