GCC 4.9, LTO: libvcl uses GZCodec but it is not linked with the implementation

This is not valid C++ and GCC now resolves the virtual calls and inlines
destructor that leads to undefined symbols.

Change-Id: I841d25bc6f994f0e73665b174994f9471597131e

include/tools/zcodec.hxx

@@ -102,7 +102,10 @@ class GZCodec : public ZCodec
 public:
                     GZCodec(){};
                     ~GZCodec(){};
-    virtual void    BeginCompression( sal_uIntPtr nCompressMethod = ZCODEC_DEFAULT );
+    virtual void    BeginCompression( sal_uIntPtr nCompressMethod = ZCODEC_DEFAULT )
+    {
+        ZCodec::BeginCompression( nCompressMethod | ZCODEC_GZ_LIB );
+    };
 };
 
 #endif

tools/source/zcodec/zcodec.cxx

@@ -413,9 +413,4 @@ sal_uIntPtr ZCodec::UpdateCRC ( sal_uIntPtr nLatestCRC, sal_uInt8* pSource, long
     return rtl_crc32( nLatestCRC, pSource, nDatSize );
 }
 
-void GZCodec::BeginCompression( sal_uIntPtr nCompressMethod )
-{
-    ZCodec::BeginCompression( nCompressMethod | ZCODEC_GZ_LIB );
-};
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */