CONFIG_I8259 is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_I8259 (not configurable)

modulename: i8259.ko

configname: CONFIG_I8259

Linux/MIPS Kernel Configuration
└─>I8259
In linux kernel since version 2.6.12  
source code:
arch/mips/kernel/i8259.c