Only compile device codegen for device architectures

Change the default for ART_TARGET_CODEGEN_ARCHS to svelte, so that only
the architectures used on the device are included in the device
libraries.

Tests: m -j test-art-target
Bug: 30928847
Change-Id: I95c8a77a5520a1030abcd45e8bb6f56bc8fc7814
1 file changed