The VDSO soname varies by architecture.

From http://man7.org/linux/man-pages/man7/vdso.7.html:

       user ABI   vDSO name
       ─────────────────────────────
       aarch64    linux-vdso.so.1
       arm        linux-vdso.so.1
       ia64       linux-gate.so.1
       mips       linux-vdso.so.1
       ppc/32     linux-vdso32.so.1
       ppc/64     linux-vdso64.so.1
       s390       linux-vdso32.so.1
       s390x      linux-vdso64.so.1
       sh         linux-gate.so.1
*      i386       linux-gate.so.1
*      x86-64     linux-vdso.so.1
       x86/x32    linux-vdso.so.1

Note that Android "x86" is Linux's "i386", which is the odd one out
amongst Android's supported architectures.

Bug: http://b/72831787
Test: ran tests
Change-Id: I0a28127af042e2fd7673f24bbb30f8a50556cf96