Revert "include: move BUG_*() macros to separate header"
This breaks the xf86-input-synaptics driver:
synaptics.c: In function 'clickpad_guess_clickfingers': synaptics.c:2638:5: error: implicit declaration of function 'BUG_RETURN_VAL' [-Werror=implicit-function-declaration] 2638 | BUG_RETURN_VAL(hw->num_mt_mask > sizeof(close_point) * 8, 0);
This reverts commit 442aec22.
cc @metux