Add QPDF_DLL to public destructors (fixes #220)

A few public destructors were missing QPDF_DLL, which could cause some
Windows applications to fail to link.

include/qpdf/Pl_QPDFTokenizer.hh

@@ -44,11 +44,15 @@ class Pl_QPDFTokenizer: public Pipeline
     // Whatever pipeline is provided as "next" will be set as the
     // pipeline that the token filter writes to. If next is not
     // provided, any output written by the filter will be discarded.
+    QPDF_DLL
     Pl_QPDFTokenizer(char const* identifier,
                      QPDFObjectHandle::TokenFilter* filter,
                      Pipeline* next = 0);
+    QPDF_DLL
     virtual ~Pl_QPDFTokenizer();
+    QPDF_DLL
     virtual void write(unsigned char* buf, size_t len);
+    QPDF_DLL
     virtual void finish();
 
   private:
@@ -60,6 +64,7 @@ class Pl_QPDFTokenizer: public Pipeline
         friend class Pl_QPDFTokenizer;
 
       public:
+        QPDF_DLL
         ~Members();
 
       private:

include/qpdf/QPDF.hh

@@ -1152,6 +1152,7 @@ class QPDF
         friend class QPDF;
 
       public:
+        QPDF_DLL
         ~Members();
 
       private:

include/qpdf/QPDFObject.hh

@@ -100,6 +100,7 @@ class QPDFObject
     {
         friend class QPDFObject;
       public:
+        QPDF_DLL
         ~Members();
       private:
         Members();

include/qpdf/QPDFWriter.hh

@@ -530,6 +530,7 @@ class QPDFWriter
         friend class QPDFWriter;
 
       public:
+        QPDF_DLL
         ~Members();
 
       private: