lib: Drop internal virXXXPtr typedefs

Historically, we declared pointer type to our types:

  typedef struct _virXXX virXXX;
  typedef virXXX *virXXXPtr;

But usefulness of such declaration is questionable, at best.
Unfortunately, we can't drop every such declaration - we have to
carry some over, because they are part of public API (e.g.
virDomainPtr). But for internal types - we can do drop them and
use what every other C project uses 'virXXX *'.

This change was generated by a very ugly shell script that
generated sed script which was then called over each file in the
repository. For the shell script refer to the cover letter:

https://listman.redhat.com/archives/libvir-list/2021-March/msg00537.html

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

docs/advanced-tests.rst

@@ -105,7 +105,7 @@ of leak:
   ==5414==    by 0x34D9021734: (below main) (in /usr/lib64/libc-2.15.so)
 
 In this example, the ``virDomainDefParseXML()`` had an error
-path where the ``virDomainVideoDefPtr video`` pointer was not
+path where the ``virDomainVideoDef *video`` pointer was not
 properly disposed. By simply adding a
 ``virDomainVideoDefFree(video);`` in the error path, the issue
 was resolved.