Extensive reorganisation of PRNG handling in FIPS module: all calls

now use an internal RAND_METHOD. All dependencies to OpenSSL standard
PRNG are now removed: it is the applications resposibility to setup
the FIPS PRNG and initalise it.

Initial OpenSSL RAND_init_fips() function that will setup the DRBG
for the "FIPS capable OpenSSL".

fips/rand/fips_rand.h

@@ -112,6 +112,7 @@ int FIPS_drbg_get_strength(DRBG_CTX *dctx);
 DRBG_CTX *FIPS_get_default_drbg(void);
 const RAND_METHOD *FIPS_drbg_method(void);
 
+int FIPS_rand_set_method(const RAND_METHOD *meth);
 
 #ifdef  __cplusplus
 }