Add extra_deps for NaCl targets
Add extra_deps for NaCl targets

Previously there were extra_deps_* for specific types of builds (newlib,
glibc, etc.). This change adds 'extra_deps' variable that works for
all types of builds.

Review URL: https://codereview.chromium.org/117663004

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@12564 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client