Some Android OS installations have very strange permissions on their
/system/etc directory, meaning that Readdir fails. Instead use
/system/framework, which is far more regular.

Change-Id: Iefc140614183cda0f875e0f6ef859f4d4eaad9da
Reviewed-on: https://go-review.googlesource.com/17078Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>