Fix pdfium-i#236: memory leaks from RenderPdf

samples/pdfium_test.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <wchar.h>
 
@@ skipping 372 matching lines @@
   if (FPDFAvail_IsLinearized(pdf_avail)) {
     fprintf(stderr, "Linearized path...\n");
     doc = FPDFAvail_GetDocument(pdf_avail, nullptr);
   } else {
     fprintf(stderr, "Non-linearized path...\n");
     doc = FPDF_LoadCustomDocument(&file_access, nullptr);
   }
 
   if (!doc) {
     fprintf(stderr, "Load pdf docs unsuccessful.\n");
+    FPDFAvail_Destroy(pdf_avail);
     return;
   }
 
   (void)FPDF_GetDocPermissions(doc);
   (void)FPDFAvail_IsFormAvail(pdf_avail, &hints);
 
   FPDF_FORMHANDLE form = FPDFDOC_InitFormFillEnvironment(doc, &form_callbacks);
   int docType = DOCTYPE_PDF;
   if (FPDF_HasXFAField(doc, &docType) && docType != DOCTYPE_PDF &&
       !FPDF_LoadXFA(doc)) {
@@ skipping 158 matching lines @@
   }
 
   FPDF_DestroyLibrary();
 #ifdef PDF_ENABLE_V8
   v8::V8::ShutdownPlatform();
   delete platform;
 #endif  // PDF_ENABLE_V8
 
   return 0;
 }