Make MemoryUtil.cpp use the correct x86_64 define.

MemoryUtil.cpp was incorrectly using the old __x86_64__ define when it should be using _M_X86_64.
It was also using _ARCH_64 when it shouldn't have which was causing an errant PanicAlert to come up in my development.
Fix a crash in ARM's CPUDetect on a malformed /proc/cpuinfo.
If a CPU string was incapable of being found we would return a null pointer, which would crash with strncpy.
Also if we couldn't get a CPU implementer we would call free() to a null pointer.
In addition, detect 64bit ARM running.
Merge pull request #446 from Sonicadvance1/Memoryutil-fix

Make MemoryUtil.cpp use the correct x86_64 define.
Remove unused mojs array from ppcState.
This was some unused array just sitting in our global ppcState struct.
I've got no idea what its use was /supposed/ to be used for if ever implemented.
Merge pull request #449 from Sonicadvance1/remove-ppcstate-mojs

Remove unused mojs array from ppcState.
Fix potential crash in Video Settings.
When Shaders folder didn't exist it would cause crash.
Merge pull request #454 from Sonicadvance1/fix-android-crash

[Android] Fix potential crash in Video Settings.
Stringify ArmCPUDetect.cpp.
Merge pull request #455 from lioncash/arm-cpudetect-fix

Stringify ArmCPUDetect.cpp.
[AArch64-emitter] Initial work on a emitter for 64bit ARM.
This being the initial work on an emitter will be buggy and mostly untested.
I've tested a few instruction encodings and am expecting most to work as long as one stays away from VFP/SIMD.
This implements mostly enough instructions to bring up an initial JIT with integer support.
There also aren't any safeguards in place, so if one passes too large of an IMM or the wrong register it'll break.