Increment RC number to RC 4 to match commits on branch.

CMakeLists.txt

@@ -329,7 +329,7 @@ ENDMACRO (CMAKE_BUILD_UTILITIES)
 SET(CMake_VERSION_MAJOR 2)
 SET(CMake_VERSION_MINOR 8)
 SET(CMake_VERSION_PATCH 1)
-SET(CMake_VERSION_RC 3)
+SET(CMake_VERSION_RC 4)
 
 # We use odd minor numbers for development versions.
 # Use a date for the development patch level.