Avoid memory leaks upon (de)compression failure

This e.g. reduces the LSan-reported leakage during CppunitTest_sd_filters_test
from

  SUMMARY: AddressSanitizer: 504104 byte(s) leaked in 4654 allocation(s).

to

  SUMMARY: AddressSanitizer: 115048 byte(s) leaked in 4639 allocation(s).

Change-Id: If922e872d9f696847face198e082144ccd5f12de

tools/source/zcodec/zcodec.cxx

@@ -82,17 +82,20 @@ long ZCodec::EndCompression()
 {
     long retvalue = 0;
 
-    if (mbStatus && meState != STATE_INIT)
+    if (meState != STATE_INIT)
     {
         if (meState == STATE_COMPRESS)
         {
-            do
+            if (mbStatus)
             {
+                do
+                {
+                    ImplWriteBack();
+                }
+                while ( deflate( PZSTREAM, Z_FINISH ) != Z_STREAM_END );
+
                 ImplWriteBack();
             }
-            while ( deflate( PZSTREAM, Z_FINISH ) != Z_STREAM_END );
-
-            ImplWriteBack();
 
             retvalue = PZSTREAM->total_in;
             deflateEnd( PZSTREAM );