arch/tile: add the <arch> headers to the set of installed kernel headers

These headers are similar to the <asm> headers that describe kernel
APIs, but instead describe aspects of the actual hardware in an
OS- and application-independent manner.  We need to include them in
the set of installed headers so that userspace tools (including glibc)
can build purely from the provided kernel headers.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/include/arch/Kbuild

+header-y += abi.h
+header-y += chip.h
+header-y += chip_tile64.h
+header-y += chip_tilegx.h
+header-y += chip_tilepro.h
+header-y += icache.h
+header-y += interrupts.h
+header-y += interrupts_32.h
+header-y += interrupts_64.h
+header-y += opcode.h
+header-y += opcode_tilegx.h
+header-y += opcode_tilepro.h
+header-y += sim.h
+header-y += sim_def.h
+header-y += spr_def.h
+header-y += spr_def_32.h
+header-y += spr_def_64.h

arch/tile/include/asm/Kbuild

 include include/asm-generic/Kbuild.asm
 
+header-y += ../arch/
+
 header-y += ucontext.h
 header-y += hardwall.h