Support third-party modules that use CamelCase

Add logic to third-party 'module' support to also work with external
packages that use CamelCase for their package "standard" variables (i.e.
<name>_{FOUND,LIBRARIES,INCLUDE_DIRS}). In particular, ParaView requires
this to use external QtTesting.

Change-Id: I645d2374ec2503eac7d226ef948f6f4b01f8de01

CMake/vtkModuleMacros.cmake

@@ -631,15 +631,21 @@ macro(vtk_module_third_party _pkg)
       endif()
     endif()
     find_package(${_pkg} REQUIRED ${__extra_args})
-    if(NOT ${_upper}_FOUND)
+    if(NOT ${_upper}_FOUND AND NOT ${_pkg}_FOUND)
       message(FATAL_ERROR "VTK_USE_SYSTEM_${_upper} is ON but ${_pkg} is not found!")
     endif()
-    if(${_upper}_INCLUDE_DIRS)
+    if(${_pkg}_INCLUDE_DIRS)
+      set(vtk${_lower}_SYSTEM_INCLUDE_DIRS ${${_pkg}_INCLUDE_DIRS})
+    elseif(${_upper}_INCLUDE_DIRS)
       set(vtk${_lower}_SYSTEM_INCLUDE_DIRS ${${_upper}_INCLUDE_DIRS})
     else()
       set(vtk${_lower}_SYSTEM_INCLUDE_DIRS ${${_upper}_INCLUDE_DIR})
     endif()
-    set(vtk${_lower}_LIBRARIES "${${_upper}_LIBRARIES}")
+    if(${_pkg}_LIBRARIES)
+      set(vtk${_lower}_LIBRARIES "${${_pkg}_LIBRARIES}")
+    else()
+      set(vtk${_lower}_LIBRARIES "${${_upper}_LIBRARIES}")
+    endif()
     set(vtk${_lower}_INCLUDE_DIRS "")
   else()
     if(_nolibs)