There was JMP_BUF defined in config.h. And SIGJMP_BUF later.

And now - JMP_BUF again. Is it enough, folks ?

Fixed again:
cc1: warnings being treated as errors
exc.c: In function 'ExcRaise':
exc.c:187: warning: passing arg 1 of 'Longjmp' from incompatible pointer type
gmake[3]: *** [exc.o] Error 1