Fix up build.scons so the install target works.
Fix up build.scons so the install target works.

This is in prep for puttin hex into the web store, via gonacl.com

BUG+none
TEST=none

git-svn-id: e22621a84199d42b34715cdc089545aeedbbf23f@1370 050acbb0-2703-11df-ab0a-9f3f633ae91d

sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk,sbc100/nativeclient-sdk