Also moves the -DHAVE_GRALLOC cflags away from the
host build as hosts do not have gralloc and mapper
3 does not have a header only library available.

Bug: b/157902551
Test: launch_cvd w/ Cuttlefish ashmem Gralloc0
Test: launch_cvd w/ Cuttlefish minigbm Gralloc3
Change-Id: I99da611a2b72f9d39df32ab9883dc52f2c081217
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/46408
Presubmit-Ready: Jason Macnak <natsu@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: Jason Macnak <natsu@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>