libxc: disable valgrind integration when building for minios

The stubdom build system incorrectly picks up on the hosts
installation of Valgrind, which cannot work in a stubdom environment.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Tested-by: Simon Martin <furryfuttock@gmail.com>
Reviewed-by: Andrew Cooper<andrew.cooper3@citrix.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
[ ijc -- s/define/defined/ ]

tools/libxc/xc_private.h

@@ -34,7 +34,7 @@
 
 #include <xen/sys/privcmd.h>
 
-#if defined(HAVE_VALGRIND_MEMCHECK_H) && !defined(NDEBUG)
+#if defined(HAVE_VALGRIND_MEMCHECK_H) && !defined(NDEBUG) && !defined(__MINIOS__)
 /* Compile in Valgrind client requests? */
 #include <valgrind/memcheck.h>
 #else