- new LIBTCC API tcc_setjmp() to allow longjmps & signals
from compiled code back to libtcc per TCCState
- new LIBTCC API tcc_set_backtrace_func() to handle backtrace output
- move c/dtor/atexit stuff to runtime (lib/runmain.c)
- move bt-log.o into libtcc1.a
- add timeouts to github action (beware, it did happen to hang
infinitely in the signal handler at some point)