ARM support?

Perhaps it would be convenient for user if PCM will support ARM?
I understand that this is an Intel library, but support for other CPU models could make this library more common.
And more widespread.

Compile error on ARM64:

```
"=a" (info.reg.eax), "=b" (info.reg.ebx), "=c" (info.reg.ecx), "=d" (info.reg.edx) : "a" (leaf));
^
/KNP/third-party/pcm/39b70acffa902cad8124c06dd0292ed48447644f/src/types.h:1648:27: error: invalid output constraint '=a' in asm
"=a" (info.reg.eax), "=b" (info.reg.ebx), "=c" (info.reg.ecx), "=d" (info.reg.edx) : "a" (leaf), "c" (subleaf));
```