Hello grischka,
Your commit caebbc3, "tccgen: scope levels for local symbols", breaks test 60_enum_redefinition on 32-bit Ubuntu 15.10. The test should error out saying "error: struct/union/enum already defined", but now it errors saying "main not defined". If a trivial main is added, it does not produce any errors. So your change apparently removed a previously tested bit of error reporting.
Let me know if you need more specifics about my platform to figure out the problem.