Get alloca() right...

src/Hist.cc

@@ -10,13 +10,12 @@
  * Illinois Open Source License; see the file LICENSE.partiview for details.
  */
 
-#if unix /* but not WIN32 */
 #ifdef __APPLE__
-  #define alloca(size) __builtin_alloca(size)
-#endif
-  /* do other unices need alloca.h? */
+# define alloca(size) __builtin_alloca(size)
+#elif unix
+# include <alloca.h>
 #else
-#include "winjunk.h"
+# include "winjunk.h"
 #endif