Disable findbug for all java targets with reources

Dummy.java is a common pattern for gyp to generate almost-empty jars, so
that when findbug scans the jar file, it does not panic.

This CL also disables findbug for android_tools folder, so that it no
longer pester clankers.

BUG=498585
Change-Id: I7c6586ac5977113f1643ccc5c265319b21712eaa
Reviewed-on: https://chromium-review.googlesource.com/285319
Reviewed-by: Aurimas Liutikas <aurimas@chromium.org>
Commit-Queue: Aurimas Liutikas <aurimas@chromium.org>
Tested-by: Aurimas Liutikas <aurimas@chromium.org>