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>
diff --git a/arch/tile/include/asm/Kbuild b/arch/tile/include/asm/Kbuild
index aec60dc..0bb4264 100644
--- a/arch/tile/include/asm/Kbuild
+++ b/arch/tile/include/asm/Kbuild
@@ -1,5 +1,7 @@
 include include/asm-generic/Kbuild.asm
 
+header-y += ../arch/
+
 header-y += ucontext.h
 header-y += hardwall.h