Work around reversed architecture specific includes

Soong is changing to prepend architecture specific include directories
to the shared include directories.  This breaks libunwind, which
expects to find include/libunwind_i.h before
include/tdep-<arch>/libunwind_i.h.  To keep the includes in the right
order, pass "include" as an architecture specific include for every
architecture.

Test: mega device build
Change-Id: I71626492c9b853414d853cd02de832fd30333896