GN Incremental Install: Don't use proguarded dex when is_debug = false
Release mode is often used to test native code performance, and so
incremental install is useful with is_debug = false. When proguard is
enabled however, incremental are currently broken.
This change forces _incremental targets to use non-proguarded .dex files
even when is_debug = false.
It also fixes the install step when only a single dex file exists.
BUG=559306
Review URL: https://codereview.chromium.org/1471393002
Cr-Commit-Position: refs/heads/master@{#361762}
4 files changed
