Hide mutated variant in non-make builds.

This CL hides (using Module.Properties.PreventInstall) either the
sanitized or stock variant for non-make embedded builds (based on
whether a sanitizer is enabled or not) so we don't have duplicate
rules for installing the same target.

Bug: 30227045
Test: OUT_DIR=out build/soong/scripts/build-ndk-prebuilts.sh # no
longer generates a duplicate build error.

Change-Id: I0b2dbb0afd5d426b32da67f951e2a4f9fbb3f3b9