ENH: Enable cvs update test with CMake before 2.6

When CMake is built by CMake 2.4 or lower the FindCVS module is not
available.  In that case we activiate CTest.UpdateCVS by searching for
the cvs command directly.

Tests/CMakeLists.txt

@@ -857,7 +857,12 @@ ${CMake_BINARY_DIR}/bin/cmake -DVERSION=CVS -P ${CMake_SOURCE_DIR}/Utilities/Rel
       MARK_AS_ADVANCED(CTEST_TEST_UPDATE_CVS)
     ENDIF(UNIX)
     IF(CTEST_TEST_UPDATE_CVS)
-      FIND_PACKAGE(CVS QUIET)
+      IF(EXISTS ${CMAKE_ROOT}/Modules/FindCVS.cmake)
+        FIND_PACKAGE(CVS QUIET)
+      ELSE(EXISTS ${CMAKE_ROOT}/Modules/FindCVS.cmake)
+        FIND_PROGRAM(CVS_EXECUTABLE NAMES cvs)
+        SET(CVS_FOUND ${CVS_EXECUTABLE})
+      ENDIF(EXISTS ${CMAKE_ROOT}/Modules/FindCVS.cmake)
     ENDIF(CTEST_TEST_UPDATE_CVS)
     IF(CTEST_TEST_UPDATE_CVS AND CVS_FOUND)
       SET(CTestUpdateCVS_DIR "CTest UpdateCVS")