As was done with LLVM (https://swiftshader-review.googlesource.com/c/SwiftShader/+/35988),
implement Sinh and Cosh in terms of Exp for Subzero. Both backends now
call into EmulatedReactor. This is not the right solution, as Reactor
should be implemented in terms of std cosh/sinh or intrinsics, as per
b/149110874.

Bug: b/145754674
Change-Id: I8f513e46fb4af270a847343e4b561927aaad1560
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41009Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Antonio Maiorano <amaiorano@google.com>