Match x64 optimization settings with x86, optimize zlib

This just changes the optimization settings for everything so that x64 and x86 match, and makes it so that zlib is always optimized even in a debug build.

Optimizing zlib in debug builds improves the initial load time significantly.

The changes to the x64 build improve its performance by approximately 3%.

Something interesting: this makes #1453 present even on x64.  I actually think that's a good thing (having the same bugs on x32 and x64), and I think knowing that will help potentially fix the issue there.

However, the Kingdom Hearts skew issue is still x86 only and doesn't occur on x64 as a result of this change.

-[Unknown]