Fix typo in OPENSSL_malloc.pod

CLA: trivial

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/13632)

doc/man3/OPENSSL_malloc.pod

@@ -101,7 +101,7 @@ before ultimately calling OPENSSL_free().
 
 OPENSSL_cleanse() fills B<ptr> of size B<len> with a string of 0's.
 Use OPENSSL_cleanse() with care if the memory is a mapping of a file.
-If the storage controller uses write compression, then its possible
+If the storage controller uses write compression, then it's possible
 that sensitive tail bytes will survive zeroization because the block of
 zeros will be compressed. If the storage controller uses wear leveling,
 then the old sensitive data will not be overwritten; rather, a block of