[FastISel][AArch64] Lower sin/cos/pow to runtime lib calls.

Also lower sin/cos/pow to runtime lib calls.

This fixes rdar://problem/18343468.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217839 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Make AArch64FastISel class final. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217840 91177308-0d34-0410-b5e6-96231b3b80d8