Merge branch 'feature/kostyantyn/e-acsl-gcc' into 'master'

`e-acsl-gcc.sh` issues with development and installed versions of the E-ACSL plugin

Previously `e-acsl-gcc.sh` (if used on its own and not through `ptests`) always used an installed version of the instrumentation engine, even if the script has been run locally and used local RTL. This merge request fixes this issue. 

See merge request !41