test/bio_comp_test.c: Initialize pointer to avoid undefined behavior

test/bio_comp_test.c: Initialize pointer to avoid undefined behavior

If the allocation for "original" fails, "result" may be freed without being
properly initialized. Since result could hold a random value due to its
assignment in do_bio_comp_test(), freeing it without initialization is unsafe
and may lead to undefined behavior.

Fixes: 12e96a2360 ("Add brotli compression support (RFC7924)")
Signed-off-by: JiashengJiang <jiasheng@purdue.edu>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27569)