Your listing of the suspect file is weird because the resulting file
name is jmp_buf instead of jmp_buf.h, so you should ask for help from
someone who can look over your shoulder. In any case, if you decide
to remove the suspect file and replace it, here's my copy of
/usr/include/jmp_buf.h from a RedHat 4.2 GNU/Linux system:
#ifndef _JMP_BUF_H
#define _JMP_BUF_H
#if defined(__i386__)
# include <i386/jmp_buf.h>
#elif defined(__mc68000__)
# include <m68k/jmp_buf.h>
#else
# error architecture not supported by Linux C library
#endif
#endif /* _JMP_BUF_H */