renderscript: go from deprecation to removal

[enh-google]

(http://b/206676167 is the internal bug for the overall "remove renderscript", http://b/255624710 the more specific "remove *.rscript files from the tree".)

renderscript's been deprecated for a while, but there was no real motivation (and some downside) to actually remove it until now. with risc-v, we either have to (a) backport risc-v support to a decade-old fork of llvm, (b) forward port renderscript to current llvm, or (c) finally remove renderscript. despite the unfortunate disruption to legacy code, option (c) is the least difficult of these choices.

i've removed all the renderscript from frameworks/av/ already (after proving it was unused), and obviously all the renderscript tools and the CTS tests of renderscript itself are easy to delete, but we'll need to manage the Studio side of things (they ship some of the tools).

the main issues are these camera tests, all of which will need to be rewritten:

https://cs.android.com/search?q=f:%5C.rscript$%20-f:cts%2Ftests%2Ftests%2Frenderscript%20-f:cts%2Ftests%2Ftests%2Frscpp%20-f:rsblas%20-f:frameworks%2Fcompile%20-f:frameworks%2Frs%20-f:development%2Fsamples&sq=package:%5Eandroid-internal$

[enh-google]

right now there's one Camera PTS test that still needs rewriting, but all the other uses of renderscript have been removed.

i've just uploaded https://android-review.googlesource.com/c/platform/cts/+/2644595 which will mean that -- while the renderscript tests will continue to be built for riscv64 cts -- they won't be run. which i think is "good enough" for now. we'll keep fighting the renderscript removal fight, but this should be enough to unblock riscv64 for now?

[enh-google]

heading in a different direction now: https://android-review.googlesource.com/c/platform/frameworks/base/+/2743418 disallows renderscript scripts (not intrinsics) for apps whose target api level is >= V.