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.
Stringify ArmCPUDetect.cpp.
Merge pull request #455 from lioncash/arm-cpudetect-fix

Stringify ArmCPUDetect.cpp.