Also don't reset memory after it's allocated if we do that with
calloc.

The xine_xmalloc() function is going to be deprecated, as its
behaviour is rarely needed as such, and it's thus misused.

With this, almost all uses of xine_xmalloc() with static size (for
instance the value returned by sizeof()) or with a size that is
guaranteed not to be zero (like strlen()+1) are replaced with calls to
either calloc(1, ...) or malloc().

malloc() is used whenever the allocated memory is going to be
immediately overwritten, while calloc() is used in every other case,
as it sets the whole memory area to zero.

--HG--
extra : transplant_source : %8F%98%EC%02%1E%83%F0s%06X%83C%205Y%80%B12%CC%E1

This patch drops support for RV20.

--HG--
extra : transplant_source : %E0%D0%C5%8B%BEU%DD%24%5D7%1F%ADV%AD%EB%23%CBU%80%EB

For contributed code, leave whatever the version we last synced for is using
to make simpler future syncs.

* Use arrays and loops instead of chained if()s.
  This reduces code size a little.
* Try to dlopen drvc.so instead of just checking for its existence.
  The old code could, for example, try to use a dir containing 32-bit libs
  on a 64-bit system. (Not that I'd expect this to happen, of course...)