The Android loader looks for the symbol `HMI` which describes the module
and provides pointers to the initial entrypoints. Add a minimal
implementation of that.

Based on docs: https://source.android.com/devices/graphics/implement-vulkan#driver_emun
Bug: b/122837488
Change-Id: I367bac2046368bc8a08334cfac2f339ca2c1eb5f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28410Tested-by: Chris Forbes <chrisforbes@google.com>
Presubmit-Ready: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>