Misc improvements for GCC 4.3

* Depends on legacy versions of gmp and mpfr for stability.
* Refined configure options.
  - Enable checking as release.
erlang-r13: don't use deprecated method
Merge pull request #125 from manphiz/gcc43

Misc improvements for GCC 4.3
Miscellaneous improvements for GCC 4.5

* Enable graphite loop optimization.
  - Depends on legacy versions of support libraries.
* Other configure option improvements.
  - Enable checking as release.
  - Enable libstdc++ time.