option now only indicates whether we want automatic backtrace at
an error.
if (SCM_ENTER_FRAME_P || SCM_BREAKPOINTS_P) CHECK_ENTRY = 1;\
if (SCM_APPLY_FRAME_P || SCM_TRACE_P) CHECK_APPLY = 1;\
if (SCM_EXIT_FRAME_P || SCM_TRACE_P) CHECK_EXIT = 1;\
- scm_debug_mode = SCM_DEVAL_P || SCM_BACKTRACE_P || CHECK_ENTRY || CHECK_APPLY || CHECK_EXIT;\
+ scm_debug_mode = SCM_DEVAL_P || CHECK_ENTRY || CHECK_APPLY || CHECK_EXIT;\
scm_ceval_ptr = scm_debug_mode ? scm_deval : scm_ceval;\
}