Don't build x86-only code on arm/riscv.

The upstream makefiles include this for x86 and x86-64, so I've done the same.

Bug: http://b/351833436
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:9848999cd77cfd69b5a355c6e237b3596ffa0459)
Merged-In: I5dfbd3a505ad7a656eeb677c68d3782572759e91
Change-Id: I5dfbd3a505ad7a656eeb677c68d3782572759e91
1 file changed