Fix linux compilation of ed25519_ref10

Our integer-definition headers apparently suck in a definition for
select(2), which interferes with the select() in ge_scalarmult_base.c

src/ext/ed25519/ref10/ge_scalarmult_base.c

@@ -1,6 +1,10 @@
 #include "ge.h"
 #include "crypto_uint32.h"
 
+/* Rename this so as not to interfere with select() which torint.h apparently
+ * grabs. :p */
+#define select ed25519_ref10_select
+
 static unsigned char equal(signed char b,signed char c)
 {
   unsigned char ub = b;