This builds with gcc 4.8.2 (and earlier), since gcc stdlib has definition for min/max functions. But for clang you need to include MIN function/macro based on your system type (hxindex.c does not link without it).
Specifically on Mac OS X you need to modify the hxindex.c like this:
--- hxindex.c 2013-07-25 17:22:53.000000000 -0400
+++ hxindex.c.patched 2014-03-11 10:05:55.000000000 -0400
@@ -43,6 +43,7 @@
* Version: $Id: hxindex.c,v 1.20 2013-07-25 21:04:05 bbos Exp $
*
**/
+#include <sys/param.h>
#include "config.h"
#include <assert.h>
#include <locale.h>
@@ -439,7 +440,7 @@
/* Count how many subterms are equal to the previous entry */
i = 0;
- while (i < min(term->nrkeys, globalprevious->nrkeys) &&
+ while (i < MIN(term->nrkeys, globalprevious->nrkeys) &&
!folding_cmp(term->sortkeys + i, 1, globalprevious->sortkeys + i, 1))
i++;