intercept build error handling

[gyorb]

improve intercept build error handling and detection

[dkrupp]

intercept-build created build json is empty on Ubuntu 14.04.4 LTS, clang 4.0-master

[dkrupp]

intercept-build logging does not work on Ubuntu 16 either

[whisperity]

How are you invoking intercept-build?

[whisperity]

My investigation reveals that this is an issue when intercept-build is invoked with a direct compiler invocation. It has been reported to @rizsotto. More on the thing here: rizsotto/scan-build#79.

[whisperity]

Side question @gyorb, @dkrupp: Should we just always build ldlogger, no matter what? It could be that at make package intercpt-build is available, but it moves out of your path when you are using CodeChecker. In this case, the logger automatically tries to fall back to ldlogger but fails horribly.

If we were to build ld-logger even if intercept is availabe, we could make this transition a lot more easier. And building ld-logger doesn't increase CC's build time that much at all.

[whisperity]

@gyorb What did you mean by "improve" in the original summary?
The issue itself with intercept-build has been resolved by #610.

[gyorb]

Until we support out own ldlogger solution we can build it always into the package (use intercept-build at runtime if available).
By improvement I meant here that we should provide better error/debug messages to the users (if it is possible) when logging the compile commands fail for some reason (not just the message that the compilation command db is empty).