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="Yann E. MORIN"

 reporter_url="http://ymorin.is-a-geek.org/projects/crosstool"

 reporter_comment="EXPERIMENTAL MIPS-64 n32 toolchain."