sfrotz wants to build when doing a "make clean"

[DavidGriffith]

@tkorvola Somehow your changes to add sfrotz have resulted in the build process wanting to build sfrotz first before doing a "make clean". Would you please take a look at this?

[DavidGriffith]

I think I fixed it. The original sfrotz Makefile was doing something weird. I'll push a fix for this later on today.

[tkorvola]

It doesn't compile but it uses the C preprocessor to generate dependency information in *.d files, then promptly removes them. I may have found a better way to manage the dependencies, on my (new) misc branch.

[DavidGriffith]

It looks good so far! I like the commit concerning keeping sound options from leaking to other interface libraries. Last night / this morning, I tried to fold in the sfrotz Makefile contents into the main Makefile, and then I realized the compile options leak problem. I managed to fix some of it, but all of it was unfixable. So I went with giving the core, blorb, and interface directories their own Makefiles, which WOULD allow this to work.

[DavidGriffith]

I see. I got on this because the not-compile would balk whenever any of the generated headers were not present.

[tkorvola]

Problem solved: sfrotz no longer includes any generated headers. Header file generation should really avoid touching the result file if it has not changed. However, a different solution was needed for the ever-changing build time stamp.

Also, the new sdl/Makefile makes no separate effort to generate dependencies. They are produced as a side effect of compilation by the rule for creating object files, in particular only if those object files are required.

[DavidGriffith]

Nice. I look forward to seeing your pull request.