RFR: aarch64: Bit count intrinsic implementation for aarch64

[Alexeev, Alexander]

Hello 

Could somebody review the patch [1] and sponsor if approved?

The patch implements _bitCount_i and _bitCount_l intrinsics with ARMv8 SIMD instructions cnt and addv
cnt - Population count per byte
addv - Add across vector

Hotspot tests suite:
Before:
Test results: passed: 826; failed: 29; error: 8
After:
Test results: passed: 826; failed: 29; error: 8

 [1] www.googledrive.com/host/0B5VQvD5uJjDQfjRBTHdsaXlBSGN1cUxnRlNncXFwdWpoRUhnRnIxV3Y1OGlqa2lPTjNuUWs