Expose QPDFObjectHandle::addTokenFilter (fixes #580)

ChangeLog

@@ -1,5 +1,9 @@
 2021-12-10  Jay Berkenbilt  <ejb@ql.org>
 
+	* Add missing QPDF_DLL to QPDFObjectHandle::addTokenFilter so that
+	it is actually accessible as part of the public interface as
+	intended. Fixes #580.
+
 	* C API: Overhaul how errors are handle the C API's object handle
 	interfaces. Clarify documentation regarding object accessors and
 	how type errors and warnings are handled. Many cases that used to

include/qpdf/QPDFObjectHandle.hh

@@ -456,6 +456,7 @@ class QPDFObjectHandle
     // be applied to a page object, and which will automatically
     // handle the case of pages whose contents are split across
     // multiple streams.
+    QPDF_DLL
     void addTokenFilter(PointerHolder<TokenFilter> token_filter);
 
     // Legacy helpers for parsing content streams. These methods are

qpdf/test_driver.cc

@@ -2704,8 +2704,20 @@ void runtest(int n, char const* filename1, char const* arg2)
         std::cout << "--- parseContents ---" << std::endl;
         ParserCallbacks cb;
         fx1.parseContents(&cb);
+        // Do this once with addContentTokenFilter and once with
+        // addTokenFilter to show that they are the same and to ensure
+        // that addTokenFilter is directly exercised in testing.
+        for (int i = 0; i < 2; i++)
+        {
             Pl_Buffer b("buffer");
+            if (i == 0)
+            {
                 fx1.addContentTokenFilter(new TokenFilter);
+            }
+            else
+            {
+                fx1.getObjectHandle().addTokenFilter(new TokenFilter);
+            }
             fx1.pipeContents(&b);
             std::unique_ptr<Buffer> buf(b.getBuffer());
             std::string s(
@@ -2713,6 +2725,7 @@ void runtest(int n, char const* filename1, char const* arg2)
                 buf->getSize());
             assert(s.find("/bye") != std::string::npos);
         }
+    }
     else if (n == 73)
     {
         try