libc/uClibc: workaround for a MIPS TLS issue

Some macros declarations were missing, so we duplicate them.
See the added patch description for more information.

----> THIS IS A DIRTY HACK! <----

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 reporter_name="unknown"

 reporter_url="http://iphonelinux.org/index.php/Glibc_toolchain_using_crosstool-NG"

 reporter_comment="An (experimental) toolchain targeting the Apple's iPhone."