Add unittests target to the binary distribution (issue #1632)

- Move all tests from the top-level directory to tests/.
- Move files shared by cefclient and unittests to tests/shared/.
- Add a fused (single header/source file) version of gtest in
  tests/gtest/ with associated CMake configuration.
- Test-only headers are now exposed in include/test/. Unit test
  targets must define UNIT_TEST in order to access them.
- Replace usage of USING_CEF_SHARED with WRAPPING_CEF_SHARED for
  clarity (only the libcef_dll_wrapper target should define it).
- Remove the RENAME_DIRECTORY CMake macro which is no longer used.
- Remove C++11 usage from unittests sources for compatibility with
  the binary distribution configuration.
- Windows: Fix build errors due to chrome_elf.dll and imm32.lib
  missing from the CMake configuration.

tests/cefclient/browser/resource_util_linux.cc

@@ -3,7 +3,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "cefclient/browser/resource_util.h"
+#include "tests/shared/browser/resource_util.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -26,10 +26,11 @@ bool GetResourceDir(std::string& dir) {
   if (!pos)
     return false;
 
-  // Add "files" to the path.
-  strcpy(pos+1, "files");  // NOLINT(runtime/printf)
+  // Add "cefclient_files" to the path.
+  strcpy(pos+1, "cefclient_files");  // NOLINT(runtime/printf)
   dir = std::string(buff);
   return true;
 }
 
 }  // namespace client
+