[Support/Compression] - Change zlib API to return Error instead of custom status.

[Support/Compression] - Change zlib API to return Error instead of custom status.

Previously API returned custom enum values.
Patch changes it to return Error with string description.
That should help users to report errors in universal way.

Differential revision: https://reviews.llvm.org/D28684

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292214 91177308-0d34-0410-b5e6-96231b3b80d8