Use signed long for FPDF_GetNamedDest buffer length.

fpdfsdk/src/fpdfview.cpp

Index: fpdfsdk/src/fpdfview.cpp
diff --git a/fpdfsdk/src/fpdfview.cpp b/fpdfsdk/src/fpdfview.cpp
index 87ef3ee5b21dec21340f4ced8e596e886df6cbe3..3f6bdd94b3324146873a1e3eb06751a7ce7264f5 100644
--- a/fpdfsdk/src/fpdfview.cpp
+++ b/fpdfsdk/src/fpdfview.cpp
@@ -817,7 +817,7 @@ DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDestByName(FPDF_DOCUMENT document,FPDF_
 	return name_tree.LookupNamedDest(pDoc, name);
 }
 
-DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDest(FPDF_DOCUMENT document, int index, void* buffer, unsigned long& buflen)
+DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDest(FPDF_DOCUMENT document, int index, void* buffer, long& buflen)
 {
     if (!buffer)
         buflen = 0;
@@ -859,7 +859,7 @@ DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDest(FPDF_DOCUMENT document, int index,
     } else if (buflen >= len) {
         memcpy(buffer, utf16Name.c_str(), len);
     } else {
-        len = -1;
+        buflen = -1;
     }
     return (FPDF_DEST)pDestObj;
 }