Change rand_pool_add[_end] prototypes to match

Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/5877)

crypto/include/internal/rand_int.h

@@ -59,10 +59,10 @@ size_t rand_pool_entropy_needed(RAND_POOL *pool);
 size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte);
 size_t rand_pool_bytes_remaining(RAND_POOL *pool);
 
-size_t rand_pool_add(RAND_POOL *pool,
-                     const unsigned char *buffer, size_t len, size_t entropy);
+int rand_pool_add(RAND_POOL *pool,
+                  const unsigned char *buffer, size_t len, size_t entropy);
 unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len);
-size_t rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy);
+int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy);
 
 
 /*