Cherry-pick "Use lrand48 on Android"

Also remove from x86/libvpx_srcs.txt
Original change: https://gerrit.chromium.org/gerrit/70494/

When building x86 assembly use lrand48 instead of the
undocumented inlined _rand function.

Android now supports rand()
https://android-review.googlesource.com/97731
but only for new versions. Original workaround:
https://gerrit.chromium.org/gerrit/15744

Change-Id: I3c17cf37c40623f8353d8836fb4ac02c35a4d8b8
Merge "Cherry-pick "Use lrand48 on Android""