Fix ASTC support for GN build
Fix ASTC support for GN build

Defines in BUILD.gn files don't apply transitively to dependencies, so
we have to repeat the SWIFTSHADER_ENABLE_ASTC for the Device
subdirectory.

Note we could also use 'public_configs = [:swiftshader_libvulkan_private_config]'
but this adds more defines and build flags than what we need. Since this
is intended as a temporary workaround anyway, we're keeping it simple.

Bug: b/150600814
Change-Id: Ib06f4a22559ee58114da5841e66e59bfce9aec4a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41868
Tested-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Reviewed-by: Antonio Maiorano <86d87a6550afb6b07035c9743fa181900589f7e0@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,google/swiftshader