Generate test coverage information
Defining "COV' for make will enable generation of coverage data. Then running tests will create those data and html can be generated with "COV=y make coverage".
Coverage is generated for both C and Lua. C uses gcov. Lua is our hacky implementation.
We cannot render this merge request properly because cov does not exist in turris/updater/updaterPlease close Merge Request or change branches with existing one