add tls test macros for xtensa
add tls test macros for xtensa

http://lists.linux-xtensa.org/pipermail/linux-xtensa/Week-of-Mon-20130819/001153.html

foss-for-synopsys-dwc-arc-processors/uClibc,wbx-github/uclibc-ng,foss-for-synopsys-dwc-arc-processors/uClibc,wbx-github/uclibc-ng,brgl/uclibc-ng,wbx-github/uclibc-ng,wbx-github/uclibc-ng,foss-for-synopsys-dwc-arc-processors/uClibc,brgl/uclibc-ng,brgl/uclibc-ng,kraj/uclibc-ng,kraj/uclibc-ng,brgl/uclibc-ng,kraj/uclibc-ng,foss-for-synopsys-dwc-arc-processors/uClibc,kraj/uclibc-ng