configure: Delete config_fips.gypi when not needed

[stefanmb]

If reconfiguring without fips, do not leave stale config_fips.gypi on disk. It will be recreated if needed by re-running configure.

[rvagg]

make distclean takes care of this, I don't think this is a job for configure

[stefanmb]

@rvagg That's true, but if you run configure twice without runing distclean in between the FIPS configuration file will be left over.

This changeset resulted from an attempt at auto-detecting FIPS mode in relation to #4631. I eventually gave up on the auto-detection because I felt it complicated the Makefile too much, but in the process I noticed the config_fips.gypi file would be leftover on disk and thus was not a reliable way to detect if we are indeed compiling in FIPS mode.

However, if you think the functionality is unnecessary I can close this request.

[rvagg]

I'd like to hear other voices from @nodejs/build and @nodejs/crypto on this, I hear you on the complication but doing a clean from configure feels very wrong.

[jbergstroem]

-1 from deleting in configure but also agree that we're not catering to the problem at hand.

[jasnell]

hmm... I think I agree with @rvagg on this. If fips mode is not enabled in the second run of configure then I would simply expect the existing file to be ignored, not deleted. It should only be deleted when doing a clean

[stefanmb]

@jasnell @jbergstroem @rvagg

Sounds good, I understand the rationale and agree with it. I'll close this pull request. Thanks!

[rvagg]

can someone explain the rationale for having config_fips.gypi? the comment in there suggests its all about node-gyp, is that the only reason we have a second file?

[stefanmb]

@rvagg I introduced that file. The rationale was explained in #4023. The file is used to separate out the special linking directive needed for FIPS from that used by node-gyp, so that modules built using your FIPS-enabled Node.js installation don't also require the OpenSSL source to be present. However, I'm open to suggestions of better, low impact ways of achieving the same thing.

[rvagg]

I wish I did have a better suggestion, but this is gyp so ...