Fix build output directories in GN.

Fix build output directories in GN.

This puts the temporary build directories for the GYP builds at the same level as the main build output directory. This fixes problems where the build script converts paths to the build directory, and these get written to the GYP file. If the build directory is different relative to the source root than the GN build directory, the paths will be messed up.

Fixes some Android goma issues for compat with the GYP build.

TBR=jam@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=242775

[brettw, 2014-01-02 17:55:56]

Committed patchset #2 manually as r242775 (presubmit successful).