[analyzer] scan-build: if --status-bugs is passed, don't forget about the exit...

[analyzer] scan-build: if --status-bugs is passed, don't forget about the exit status of the actual build

Summary:
This has been bothering me for a while, but only now i have actually looked into this.
I'm using one CI job for static analysis - clang static analyzers as compilers + clang-tidy via cmake.
And i'd like for the build to fail if at least one of those finds issues.
If clang-tidy finds issues, it will fail the build since the warnings-as-errors is set.
If static analyzer finds anything, since --status-bugs is set, it will fail the build.
But if clang-tidy find anything, but static analyzer does not, the build succeeds :/

Reviewers: sylvestre.ledru, alexfh, jroelofs, ygribov, george.karpenkov, krememek

Reviewed By: jroelofs

Subscribers: xazax.hun, szepet, a.sidorin, mikhail.ramalho, Szelethus, cfe-commits

Differential Revision: https://reviews.llvm.org/D52530

llvm-svn: 343105