alloca.h is a glibc thing.

Index: xorn/tests/storage/validate.c
--- xorn/tests/storage/validate.c.orig
+++ xorn/tests/storage/validate.c
@@ -15,7 +15,7 @@
    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
 #include <xornstorage.h>
-#include <alloca.h>
+#include <stdlib.h>		/* alloca() */
 #include <assert.h>
 #include <math.h>
 #include <string.h>
