consistently return -1 in SvFileStream::PutData

for the error case

Just for consistency with the other error cases in PutData/GetData

Change-Id: Ib7fd27f9347021b3063e6eac88fd8038d5f218e0
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/176621
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

tools/source/stream/strmunx.cxx

@@ -243,7 +243,10 @@ std::size_t SvFileStream::PutData( const void* pData, std::size_t nSize )
             return -1;
         }
         else if( !nWrite )
+        {
             SetError( SVSTREAM_DISK_FULL );
+            return -1;
+        }
     }
     return static_cast<std::size_t>(nWrite);
 }