Fix/rewrite/darwinize test runner of jerry-debugger (#1756)
Fix/rewrite/darwinize test runner of jerry-debugger (#1756)

First issue was that `diff -u0` was not supported on OSX, thus got
replaced by `-U0`. Then, it turned out that test outcome was
determined based on diff's stdout, which was empty even though the
exit code was non-0 - this got changed, too.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu
jack60504/jerryscript,LaszloLango/jerryscript,bzsolt/jerryscript,martijnthe/jerryscript,zherczeg/jerryscript,bzsolt/jerryscript,bsdelf/jerryscript,grgustaf/jerryscript,jack60504/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,robertsipka/jerryscript,bsdelf/jerryscript,jerryscript-project/jerryscript,bsdelf/jerryscript,martijnthe/jerryscript,zherczeg/jerryscript,gabrielschulhof/jerryscript,LaszloLango/jerryscript,glistening/jerryscript,jack60504/jerryscript,LaszloLango/jerryscript,gabrielschulhof/jerryscript,gabrielschulhof/jerryscript,bzsolt/jerryscript,jerryscript-project/jerryscript,bzsolt/jerryscript,bsdelf/jerryscript,yichoi/jerryscript,bzsolt/jerryscript,yichoi/jerryscript,gabrielschulhof/jerryscript,robertsipka/jerryscript,jack60504/jerryscript,akosthekiss/jerryscript,yichoi/jerryscript,bsdelf/jerryscript,martijnthe/jerryscript,jerryscript-project/jerryscript,zherczeg/jerryscript,bsdelf/jerryscript,zherczeg/jerryscript,jack60504/jerryscript,robertsipka/jerryscript,robertsipka/jerryscript,zherczeg/jerryscript,grgustaf/jerryscript,akosthekiss/jerryscript,martijnthe/jerryscript,glistening/jerryscript,jerryscript-project/jerryscript,LaszloLango/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,martijnthe/jerryscript,grgustaf/jerryscript,dbatyai/jerryscript,glistening/jerryscript,robertsipka/jerryscript,grgustaf/jerryscript,akosthekiss/jerryscript,dbatyai/jerryscript,yichoi/jerryscript,dbatyai/jerryscript,martijnthe/jerryscript,grgustaf/jerryscript,glistening/jerryscript,grgustaf/jerryscript,jack60504/jerryscript,robertsipka/jerryscript,jerryscript-project/jerryscript,gabrielschulhof/jerryscript,LaszloLango/jerryscript,yichoi/jerryscript,glistening/jerryscript,glistening/jerryscript