icd: clean up alloc functions

Clean up and move alloc functions to icd-alloc.[ch].
diff --git a/icd/intel/intel.h b/icd/intel/intel.h
index 6ddd598..b342eef 100644
--- a/icd/intel/intel.h
+++ b/icd/intel/intel.h
@@ -39,6 +39,7 @@
 #include <xglWsiX11Ext.h>
 
 #include "icd.h"
+#include "icd-alloc.h"
 #include "icd-bil.h"
 #include "icd-format.h"
 #include "icd-utils.h"