Improve error detection and handling: 	Reduce _JBLEN for the i386 to what is actually used. 	Encapsulate jmp_buf and sigjmp_buf in structs. 	Enlarge jmp_buf to the same size as sigjmp_buf. 	Declare *longjmp as non-returning.
Improve error detection and handling:
	Reduce _JBLEN for the i386 to what is actually used.
	Encapsulate jmp_buf and sigjmp_buf in structs.
	Enlarge jmp_buf to the same size as sigjmp_buf.
	Declare *longjmp as non-returning.

Remove stale comments about sig*jmp not being implemented.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase