rollup merge of #24953: tamird/android-pie

This is OK to do given:
  - PIE is supported on Android starting with API 16.
  - The bots are running API 18.
  - API < 16 now has a 12.5% market share[0] as of 2015-04-29.

Closes #17437.

[0] https://developer.android.com/about/dashboards/index.html

r? @alexcrichton

src/test/run-pass/backtrace.rs

@@ -10,6 +10,7 @@
 
 // no-pretty-expanded FIXME #15189
 // ignore-windows FIXME #13259
+// ignore-android FIXME #17520
 
 use std::env;
 use std::process::{Command, Stdio};