embed: Fix alloca include for FreeBSD and NetBSD.

Signed-off-by: darc <darcagn@protonmail.com>

ports/embed/port/mpconfigport_common.h

@@ -33,6 +33,10 @@ typedef uintptr_t mp_uint_t; // must be pointer size
 typedef long mp_off_t;
 
 // Need to provide a declaration/definition of alloca()
+#if defined(__FreeBSD__) || defined(__NetBSD__)
+#include <stdlib.h>
+#else
 #include <alloca.h>
+#endif
 
 #define MICROPY_MPHALPORT_H "port/mphalport.h"