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

Transactional Memory support for POWERPC

configname: CONFIG_PPC_TRANSACTIONAL_MEM

Linux Kernel Configuration
└─>Kernel options
└─>Transactional Memory support for POWERPC
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Support user-mode Transactional Memory on POWERPC.