ppl 0.11

Closes #118.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
Gmp4: Fix legacy (not working) compiler check.

* Keg_only because of conflict with gmp.
Add legacy version of mpfr.

* Add mpfr 2.4.2 from GCC infrastructure.
Add legacy version of libmpc

* Track libmpc 0.8.1 on GCC infrastructure.