tile: support FRAME_POINTER

Allow enabling frame pointer support; this makes it easier to hook
into the various kernel features that claim they require it without
having to add Kconfig conditionals everywhere (a la mips, ppc, s390,
and microblaze).  When enabled, it basically eliminates leaf functions
as such, and stops optimizing tail and sibling calls.  It adds around
3% to the size of the kernel when enabled.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/Kconfig

@@ -26,6 +26,7 @@ config TILE
 	select HAVE_SYSCALL_TRACEPOINTS
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select HAVE_DEBUG_STACKOVERFLOW
+	select ARCH_WANT_FRAME_POINTERS
 
 # FIXME: investigate whether we need/want these options.
 #	select HAVE_IOREMAP_PROT