Misc improvements for GCC 4.3

* Depends on legacy versions of gmp and mpfr for stability.
* Refined configure options.
  - Enable checking as release.
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.
Miscellaneous improvements for GCC 4.7

* Enable graphite loop optimization.
  - Depends on legacy versions of support libraries.
* Other configure switch improvements.
  - Enable checking as release.
  - Enable libstdc++ time.
Miscellaneous improvements for GCC 4.8

* Configure options improvements.
  - Enable checking as release.
  - Enable libstdc++ time.
Update GCC 4.9 to snapshot at 20130505

* Configure options improvements.
  - Enable checking as release.
  - Enable libstdc++ time.