Revert "Fix segfualts with -O3 (gcc 4.8 mmx tests and compiling) on 32 bits systems"

As it turns out, I was only coding a workaround for a bug in g++-4.8.
In g++-4.9 there are no more segfaults.
Since g++-4.8 will never hit Debian Stable and g++-4.9 is already the
default in Debian Testing, it makes no sense keeping this.

This reverts commit bc33ac4061c0f611df050c83bd0e169c6896784b.