Remove unused Android.mk under contexthub/firmware/variant
The module names for these Android.mk files are
`libnanohub_os_argonkey`, `libnanohub_os_linux`,
`libnanohub_os_lunchbox`, and `libnanohub_os_nucleo`.
After verification, these modules cannot build any targets in Android.
This is because they ultimately call `$(BUILD_AUX_STATIC_LIBRARY)`,
which has been deprecated in Android.
(Reference: build/make/core/deprecation.mk).
Furthermore, since these modules are not dependencies for any other
targets, it should be safe to remove them.
Bug: 339559247
Bug: 339371002
Test: N/A
Change-Id: I8c79ee4a25861d2e3f85157a2d7c3d92d335c9ba
5 files changed
