This reverts commit ae7f543b7c.
Reason for revert: Enabling dexpreopt for RISC-V (there is still no
compiler support, but dex2oat runs in verification mode and does
not attempt any compilation with https://r.android.com/2510739).
Change-Id: I0a6d0416bec51131f0a54c7ff5b0e194728452b1