test/plain_c++: - refactored to share code - extended to treat default this calls and explicitly as cdecl declared ones, separately - prev point fixes implicitly on x86 a wrong dcMode setting (assumed that cdecl for methods would default to the native this call convention, but actually does not, applies cdecl verbatim) - extended aggr tests to also test explicit cdecl as well as MS thiscalls on x86 - simplified

This tests arm/thumb interwork.
Run build.sh from top-level build directory.

1. dyncall is compiled as default using Makefile-default.config
2. tests are compiled with -mthumb using Makefile-thumb.config