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/lib/cacheflush.c

@@ -36,7 +36,8 @@ static inline void force_load(char *p)
  * core (if "!hfh") or homed via hash-for-home (if "hfh"), waiting
  * until the memory controller holds the flushed values.
  */
-void finv_buffer_remote(void *buffer, size_t size, int hfh)
+void __attribute__((optimize("omit-frame-pointer")))
+finv_buffer_remote(void *buffer, size_t size, int hfh)
 {
 	char *p, *base;
 	size_t step_size, load_count;