libchromeos: minijail: do not use ld preload API functions on Android

When building for Android, do not use the minijail_run_pid_pipe* API
funtions that use LD_PRELOAD. Instead, use the *_no_preload versions
of these functions.

While there, replace the use of minijail_run_pid_pipe() with

BUG: 24577038
Change-Id: Ie29a0f762e7810587f49199679dcc9d90acd465d
TEST: unit tests pass.
2 files changed