only inflate if status from InitDecompress is good

Change-Id: Ief207205b3f05dd0ed92a2d1d30e265cbdb914e3
(cherry picked from commit 5aff1349)

-1 -> Z_ERRNO for clarity

Change-Id: I29aa8531646f416a72b89f7571b757c39705c31a
(cherry picked from commit 8cb69cc8)
Reviewed-on: https://gerrit.libreoffice.org/16826Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

tools/source/zcodec/zcodec.cxx

@@ -153,7 +153,7 @@ long ZCodec::Decompress( SvStream& rIStm, SvStream& rOStm )
                 UpdateCRC( mpInBuf, nInToRead );
 
         }
-        err = inflate( PZSTREAM, Z_NO_FLUSH );
+        err = mbStatus ? inflate(PZSTREAM, Z_NO_FLUSH) : Z_ERRNO;
         if ( err < 0 )
         {
             mbStatus = false;
@@ -220,7 +220,7 @@ long ZCodec::Read( SvStream& rIStm, sal_uInt8* pData, sal_uIntPtr nSize )
                 UpdateCRC( mpInBuf, nInToRead );
 
         }
-        err = inflate( PZSTREAM, Z_NO_FLUSH );
+        err = mbStatus ? inflate(PZSTREAM, Z_NO_FLUSH) : Z_ERRNO;
         if ( err < 0 )
         {
             // Accept Z_BUF_ERROR as EAGAIN or EWOULDBLOCK.
@@ -273,7 +273,7 @@ long ZCodec::ReadAsynchron( SvStream& rIStm, sal_uInt8* pData, sal_uIntPtr nSize
                 UpdateCRC( mpInBuf, nInToRead );
 
         }
-        err = inflate( PZSTREAM, Z_NO_FLUSH );
+        err = mbStatus ? inflate(PZSTREAM, Z_NO_FLUSH) : Z_ERRNO;
         if ( err < 0 )
         {
             // Accept Z_BUF_ERROR as EAGAIN or EWOULDBLOCK.