CONFIG_SPE is not available for thedefaultarchitecture x86.
Result is shown for architecture powerpc

SPE Support

modulename: math_efp.ko

and/or

ptrace-spe.ko

configname: CONFIG_SPE

Linux Kernel Configuration
└─>Processor support
└─>SPE Support
In linux kernel since version 2.6.15 (release Date: 2006-01-02)  
This option enables kernel support for the Signal Processing
Extensions (SPE) to the PowerPC processor. The kernel currently
supports saving and restoring SPE registers, and turning on the
'spe enable' bit so user processes can execute SPE instructions.

This option is only useful if you have a processor that supports
SPE (e500, otherwise known as 85xx series), but does not have any
effect on a non-spe cpu (it does, however add code to the kernel).

If in doubt, say Y here.

source code: