- Fix building on OpenBSD/sparc64

Index: eval_l.c
--- eval_l.c.orig
+++ eval_l.c
@@ -857,7 +857,7 @@ static const flex_int16_t yy_chk[474] =
 #include <math.h>
 #include <string.h>
 #include <ctype.h>
-#ifdef sparc
+#if defined(__sparc) && defined(__sun) && defined(__SVR4)
 #include <malloc.h>
 #else
 #include <stdlib.h>
