Check prebuilt sources during checkbuild

Add prebuilt files as dependencies during checkbuild.  This will flag
prebuilt modules that have files that don't exist as errors, and also
fix building soong modules with make native, etc.

Bug: 32332829
Test: m -j checkbuild
Test: m -j host
Change-Id: Ia4e22cb640978c181de039202baf02f4fb5a94d5