This reverts commit 0f7f8f87747ae825c3b5adeae35cbb66114d2ba1, reversing
changes made to 9f1505435877cf8f5abe7b66fb2717c7e39c1988.

As it is currently written, CallLambdaTrampoline does not return a
value. However, some of the functions that are being wrapped may
return a value that the JIT is expected to understand. A compiler
*cough cough clang* may opt to alter %rax after the wrapped lambda
returns, e.g. popping a previous value, which can clobber the
return value. If we actually have a return value, then the compiler
must not clobber it.

Fixes https://code.google.com/p/dolphin-emu/issues/detail?id=8697&can=3

Fifo: Rewrite SyncGPU

In a particular hashing heavy scene in Crazy Taxi the Murmur3 hash used 3.11% CPU time.
The new CRC32 hash in the same scene used 1.86%
This was tested on a Nvidia SHIELD Android TV with Cortex-A57s.

This will be a bit slower on the Nexus 9, the Denver CPU core is a bit slower with CRC32 texture hashing than Murmur3 texture hashing.

The new implementation has 3 options:
 SyncGpuMaxDistance
 SyncGpuMinDistance
 SyncGpuOverclock

The MaxDistance controlls how many CPU cycles the CPU is allowed to be in front
of the GPU. Too low values will slow down extremly, too high values are as
unsynchronized and half of the games will crash.
The -MinDistance (negative) set how many cycles the GPU is allowed to be in
front of the CPU. As we are used to emulate an infinitiv fast GPU, this may be
set to any high (negative) number.

The last parameter is to hack a faster (>1.0) or slower(<1.0) GPU. As we don't
emulate GPU timing very well (eg skip the timings of the pixel stage completely),
an overclock factor of ~0.5 is often much more accurate than 1.0