Revert "[bzip2] Avoid use of uninitialized memory."

This reverts commit d276bcb7f0.

The original commit did avoid the use of uninitialized memory. However,
it appears that the original commit is no longer required. The
underlying issue was resolved by a change in freetype2-testing "Build
bzip2 correctly." [0]. Prior to [0] bzip2 was built without msan, so
bzip2 writes were not tracked or considered initialized. Clearing
`buffer` in the original commit allowed msan to see the `buffer` content
initialized once in FreeType code, but msan saw no writes into buffer
from bzip2.  With bzip2 now built with msan, the bzip2 writes are
properly instrumented and msan sees the bzip2 writes into the buffer. As
a result the original commit can be safely reverted to allow for better
detection of other uninitialized data scenarios.

* src/bzip2/ftbzip2.c (FT_Stream_OpenBzip2): Revert to using `FT_QNEW`.

[0] 3c052a837a

src/bzip2/ftbzip2.c

@@ -481,9 +481,7 @@
     FT_ZERO( stream );
     stream->memory = memory;
 
-    /* Don't use `FT_QNEW` here to avoid problems with uninitialized */
-    /* memory later on if the font is malformed.                     */
-    if ( !FT_NEW( zip ) )
+    if ( !FT_QNEW( zip ) )
     {
       error = ft_bzip2_file_init( zip, stream, source );
       if ( error )