[llvm] [llvm-cov] Export decision coverage to output json (PR #144335)

[Alan Phipps via llvm-commits]

evodius96 wrote:

Hi @uthmanna, I apologize, but I ended up reverting the merge commit due to unresolved test failures.  Specifically, `tools/llvm-cov/binary-formats.c` fails due to the JSON version adjustment.  Please ensure that you can run all of the regression tests.  While you're add it, I think it's a good idea to add another test that ensures that the decision counts you've added are present in an exported JSON file.  You can extend existing test `test/tools/llvm-cov/mcdc-export-json.test` if you wish.

https://github.com/llvm/llvm-project/pull/144335