testrand: Remove testrand_finish

This removes printing of the "random run = " at the end of the tests. I
haven't seen a single case where this proved to be useful. And as of
48789dafc2, this is anyway printed only at
the end of the exhaustive tests and not the normal tests, so the
probability that this will be useful in the future is very low.

src/testrand.h

@@ -42,7 +42,4 @@ static void testrand_flip(unsigned char *b, size_t len);
 /** Initialize the test RNG using (hex encoded) array up to 16 bytes, or randomly if hexseed is NULL. */
 static void testrand_init(const char* hexseed);
 
-/** Print final test information. */
-static void testrand_finish(void);
-
 #endif /* SECP256K1_TESTRAND_H */