krb5: reorganise crypto.c

lib/krb5/crypto.c was a large, monolithic block of code which made
it very difficult to selectively enable and disable particular
alogrithms.

Reorganise crypto.c into individual files for each encryption and
salt time, and place the structures which tie everything together
into their own file (crypto-algs.c)

Add a non-installed library (librfc3961) and test program
(test_rfc3961) which builds a minimal rfc3961 crypto library, and
checks that it is usable.

lib/krb5/store.c

@@ -222,30 +222,6 @@ krb5_storage_get_eof_code(krb5_storage *sp)
     return sp->eof_code;
 }
 
-KRB5_LIB_FUNCTION krb5_ssize_t KRB5_LIB_CALL
-_krb5_put_int(void *buffer, unsigned long value, size_t size)
-{
-    unsigned char *p = buffer;
-    int i;
-    for (i = size - 1; i >= 0; i--) {
-	p[i] = value & 0xff;
-	value >>= 8;
-    }
-    return size;
-}
-
-KRB5_LIB_FUNCTION krb5_ssize_t KRB5_LIB_CALL
-_krb5_get_int(void *buffer, unsigned long *value, size_t size)
-{
-    unsigned char *p = buffer;
-    unsigned long v = 0;
-    int i;
-    for (i = 0; i < size; i++)
-	v = (v << 8) + p[i];
-    *value = v;
-    return size;
-}
-
 /**
  * Free a krb5 storage.
  *