tools: Partially revert "Cross-compilation fixes."

This partially reverts commit 16504669c5.

Doesn't look like much of 16504669c5
actually remains due to passage of time.

Of the 3, both Python and pygrub appear to mostly be building just fine
cross-compiling.  The OCAML portion is being troublesome, this is going
to cause bug reports elsewhere soon.  The OCAML portion though can
already be disabled by setting OCAML_TOOLS=n and shouldn't have this
extra form of disabling.

Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Acked-by: Wei Liu <wl@xen.org>

tools/Makefile

@@ -39,12 +39,9 @@ SUBDIRS-$(CONFIG_X86) += debugger/gdbsx
 SUBDIRS-$(CONFIG_X86) += debugger/kdd
 SUBDIRS-$(CONFIG_TESTS) += tests
 
-# These don't cross-compile
-ifeq ($(XEN_COMPILE_ARCH),$(XEN_TARGET_ARCH))
 SUBDIRS-y += python
 SUBDIRS-y += pygrub
 SUBDIRS-$(OCAML_TOOLS) += ocaml
-endif
 
 ifeq ($(CONFIG_RUMP),y)
 SUBDIRS-y := libs libxc xenstore